The Problem
The three traditional attributes of God (in whichever tradition it is) are omnipotence, omniscience, and omnibenevolence. Under the assumption that reasonable discussion of God is possible, these three attributes cannot be realized simultaneously and to their fullest extent while retaining logical consistency.
We can see this by supposing that God fully embodies all three attributes to their fullest extent while considering the problem of evil. If God has the power to stop all evil and complete awareness of all evils that exist, then God cannot be fully omnibenevolent while permitting evil to continue. We may argue that God's "good" is a truer "good" than humanity's "good," and that evil is somehow "part of God's plan," but this voids the word "good" of any coherent meaning. A similar, if lengthier argument can be used to dissolve the concepts of "omnipotence" and "omniscience" into a soup of ambiguity. We don't really gain anything from caveating our definitions into oblivion.
While it is not unreasonable to resolve this seeming paradox by adopting the position that God is simply beyond all description, definition, language, or reason - so that the statement "God is omnipotent, omniscient, and omnibenevolent" remains true no matter what - it's also exceedingly boring. There isn't a whole lot we can learn from or about the unknowable, imperceptible, and indescribable, and relegating God to the realm of inscrutable cosmic vagueries largely robs It of any significance (except, perhaps, as a tool for the exploration of existential horror.)
The point is, if we wish to have any kind of genuinely meaningful discussion about God, then we have no choice but to define the properties of God in a way that's consistent (or at least paraconsistent) with the way the that semantics works. And this requires us to weaken at least one of the three aspects of God.
The question is then: How can we maximize the three attributes of God while remaining logically consistent?
I'm not sure how to go about this one.
Approaching it mathematically, I might consider functions "P," "S," and "B," mapping descriptions of God's omnipotence, omniscience, and omnibenevolence, respectively, to the interval [0,1]. The task is then to find mutually consistent descriptions "dp," "ds," and "db" such that the value of "P(dp)+S(ds)+B(db)" is a global maximum over the domain of consistent descriptions (we can alter this expression to weigh each attribute differently, if we so choose.) The problem with this approach is that there doesn't seem to be an especially reasonable way to quantify the extent to which an arbitrary description realizes an attribute of God. Furthermore, since the space of all descriptions is at most countably infinite, the most common analytical methods* of optimization won't be available even if there is.
The only definitive measure seems to be the number of attributes being weakened, but there is an argument to be made that a certain version of God with full omnipotence and particular forms of weak omniscience and omnibenevolence might embody God more than one with a particular form of weak omnipotence and full omniscience and omnibenevolence.
This is where I get stuck. Without a "most logical way" to define an order on the space of descriptions of each attribute, there's no sensible way to compare consistent characterizations of God except by the number of attributes weakened. Yet this number alone is likely insufficient for measuring the strength of a characterization. Even if it were, there's no reason to choose between, say, weak omnipotence, with full omniscience and omnibenevolence, and full omnipotence and omniscience, with weak omnibenevolence.
I suppose that I could have God exist in some kind of undecided logical superposition of "equally" weakened states - so that the assertion "There exists an index n such that God is Cn" is decidably true for some set of independently consistent characterizations {C1,C2,C3,...}, while "God is C1," "God is C2," ..., are all undecidable - but that's just being obnoxious for no good reason (although it would be hilarious to see a debate about the nature of God pointlessly derailed by the realization that the debaters had all committed the same modal fallacy.)
My Thoughts:
With all that said, my favourite characterization so far has been weak omnipotence, with full omniscience and omnibenevolence, with God's omnipotence being defined as follows:
"Given any possible [future] state of affairs "U," God may intervene in such a way that after some finite length of time "U" is the present state of affairs."
This gives God the power to do anything eventually, but not to do everything instantaneously, thus resolving the problem of evil by way of "God will ultimately rid the world of evil, but it will take time." I like this characterization because it doesn't directly contradict any known truths about God (I have yet to find a canonical description which requires that the action of God on reality be instantaneous), and it suggests that the only real limit to God's power is "reality must be consistent."
This does get into a spot of trouble with relativity, though, since it's unclear exactly what is meant by "possible," "present," and "state of affairs." If we're not careful, this can end up being indistinguishable from "God only has the power to travel a continuous path across block universes." (although, that would make the Bible an account of God's journey across the multiverse, which is kind of awesome.)
Also of note: full omnipotence and omnibenevolence with weak omniscience is inconsistent wherever 1) God is aware of Its omnipotence and 2) full omniscience would aid in the exercise of God's omnipotence or omnibenevolence. Supposing this grants God the capacity and motive for granting Itself full omniscience while forbidding God from doing so. We could counter this by weakening omniscience to the point that God doesn't realize or understand how omniscience could be useful, but I think that an all-powerful, all-loving, dumbass is definitively less "Godly" than a being which fully embodies two aspects and almost fully embodies the third. Alternatively, perhaps some form of ignorance is simply necessary for omnipotence and omnibenevolence, and this fact is included among God's knowledge. Perhaps ignorance is strength, and we are either too stupid or too intelligent to know it?
In any case, the weakening of omniscience in a non-stupid way requires that God knows at most everything but the fullness of Its omnipotence, or that full omniscience is not necessary or beneficial for the exercise of omnipotence and omnibenevolence. Technically, we might still be able to get away with full omnipotence, full omnibenevolence, and almost full omniscience if we suppose that "God is aware of everything except Its ability to grant Itself full omniscience," and "The ability of God to grant Itself full omniscience is logically independent of all other truths," but 1) I find the truth of the latter claim to be less likely than that of "God's just an idiot," and 2) this is such an utterly contrived manipulation of logic that it feels less like a solution and more like an exploit.
Edit: Operationalizing "Omni-XYZ"
As Frank points out in comments, we need to clarify the meanings of "omnipotent," "omniscient," and "omnibenevolent" to prevent everything from devolving into opinion. I had hoped to avoid this, since it might lead to discounting interesting alternative perspectives but needs must, I suppose.
Definition: (Potential) the potential of an entity is the capacity of that entity to alter the present state of affairs. In particular, an omnipotent entity is one with the capacity to alter the present state of affairs in every way.
Note that the notion of potential is not well-founded, so the potential of an entity is counted in the state of affairs which that entity may alter.
Definition: (Knowledge) The knowledge possessed by an entity is the set of all true statements known by that entity to be true (I will not distinguish between "true belief" and "justified true belief," because it doesn't add anything.) In particular and omniscient entity is one whose knowledge includes all truths.
Formally, we can express the knowledge of each entity as a modal operator. As is the norm for modal logics, knowledge of knowledge is included in knowledge (specifically "from KiP and P, infer KiKiP," where Ki is the i-th modal operator.) Yes this leads to recursion. No it doesn't matter.
Definition: (Benevolence) Benevolence is the desire and tendency of an entity to seek the happiness of others, and to prevent or alleviate suffering. In particular, an omnibenevolent entity is one which seeks to guarantee the happiness of all entities and eliminate all suffering.
We can pretend like we don't understand what this means, but let's be honest: kindness is kindness and suffering is suffering, there are complexities and nuances to both, but it's not some kind of enigmatic riddle. Giving a cold person a blanket is kindness and shooting them in the knee will cause them suffering.
An omnipotent, omniscient and omnibenevolent being is thus one with:
the capacity to induce any state of affairs
knowledge of all truths
the desire and tendency to cause happiness and eliminate suffering in all cases
We take as axioms that God possesses potential, knowledge and benevolence, and that God possesses these attributes to the greatest extent that it is possible for any entity to possess these attributes.***
One may or may not wish to exclude claims of the discourse from the state of affairs to prevent paradoxes (such as might be caused by God altering these definitions or the notion of "truth.") While this does prevent many paradoxes from forming, it is not strictly necessary for the prevention of paradoxes in every case.** I leave it up to the reader to decide the permissible extent of self-reference in interpreting "state of affairs."
Footnotes
* "Analytical methods" as in the methods employed in the study of mathematical analysis, not the methods of analytic philosophy. I mean to highlight that the mapping is not generally differentiable, or even continuous.
** For examples, I would recommend Douglas Hofstadter's Metamagical Themas. There are also more rigorous texts on self-modifying abstract machines, but these are a lot drier and I couldn't name them.
*** Yes, this means that God is an entity. The word "God" is a singular proper noun whether spoken in English or Latin, so arguing that God is beyond what can be considered an "entity" amounts to saying "we can't talk about God," which once more, is a logically sound but incredibly boring point of view.
self-reference tag because 90% of the actual work in making God consistent has to do with self-reference (ex: "God has the power to make Itself powerless," "God does not know that It is omniscient," "God seeks Its own gratification," etc.)