TL/DR
It's whichever floats your boat, my dude.
Serious Reply
There are a couple of problems here. The first is, what do you mean by "better"? Better in what sense? Unless you define what you mean by better, you aren't asking a coherent question.
If you are asking what some standards are that philosophers use to judge, say, an academic paper, that is an answerable question. For a paper to be "good", it should be valuable, well reasoned, focused, and well researched. Conclusions should follow logically from premises, premises should be explicit, the purpose of the paper should be clearly stated, and the work of other philosophers on the topic should be referenced where relevant. And of course the paper should say something new about the topic, or in the case of a meta-analysis, summarize and critique a lot of previous work in a new way.
If you are instead looking for some sort of "absolute good", there isn't one and can't be one. Science also can't answer questions about some sort of "absolute reality", and generally speaking that doesn't stop us from increasing the predictive power of science, and the lack of an "absolute good" doesn't stop us from making progress in moral philosophy.
In the United States, up until 1974, women in the United States could not get credit cards. Today, they can. This is largely the result of applied moral philosophy in the form of social agitation. Is this progress?
That depends on what you value. There are people who think it is not. You can point out that literally everyone is objectively better off if women can get credit cards, but if the person you are talking to doesn't value being "better off" more than they value the subjugation of women, you aren't going to get anywhere because they don't value the things that you value.
We can look at the philosophies of the past and see that some of them were based on false assumptions about the nature of reality. A philosophy that relies on objectively false things is generally considered worse than one that does not. However, in an absolute sense, someone can always ask "but why tho" and refuse to agree that it matters whether the assumptions of a philosophy are objectively false.
So yes. You have to start with something. What you (or at least what I) undeniably have is experience. Experience is undeniably happening. I can reason pretty easily from "I experience the world" to "you experience the world", and from there I can build a moral philosophy that includes compassion, which gets me to equity, and so on.
I can do all that, but then some troll will come along and try to justify enslaving people and while I can point out the numerous practical and philosophical reasons that this is a bad idea, I can't make them value these things.
A note on the phrase "experience the world", because I'm pretty sure someone, at some point, will say that I'm assuming the world exists but really I might be a brain in a jar or whatever.
For these purposes, it does not matter if I am a brain in a jar. The preponderance of the evidence suggests that if I am a brain in a jar, you are also a brain in a jar, and therefore you exist in the same sense that I do. Solipsism fails under rational analysis.
Of course, you have to value rational analysis to care if solipsism fails under rational analysis, but, you know, whatever.
