There are too many complex variables to make your question answerable. What works for one individual in a particular situation may not work for another.
The maxim ignorance is bliss speaks volumes. As a long-time political activist, I find myself weighed down by the ever bigger socio-political-environmental problems weighing down on us. Although I despise the muddled masses who are addicted to video games and football, I'm often envious of their apparent carefree attitudes.
One problem is the fact that once you learn about something bad, you can't always unlearn it. So if you say "To hell with climate change," I'm just going to party, is that an example of ignorance or escapism?
In his classic work A Sand County Almanac, Aldo Leopold wrote about the penalty of having an ecological consciousness. One person can look at a landscape brightened by millions of bright yellow blossoms and proclaim it beautiful. However, a naturalist might moan, "But those are an introduced species that's wiping out plants that native animal species depend on. And what happened to the herds of bison and elk that once grazed here?"
Leopold isn't generally recognized as a philosopher (as far as I know), but some of his writings are clearly philosophical.
Getting back to your unanswerable question, an important keyword is selfishness. Happiness can be extremely selfish if it comes at the expense of others. Which brings us to the question of responsibility.
What responsibilities, if any, do we have to our families, friends, neighborhoods, communities, countries or the environment? When we embrace ignorance as an antidote to depression, we may be letting all the above down.
In the end, it comes to a question of balance. That can mean pacing yourself. Instead of reading about depressing truths 24 hours a day, set aside a few hours for some healthy escapism. You can also try to brainstorm ways to make the depressing things less depressing.
For example, if you lived in a wretched country where everyone was starving, wouldn't it cheer you up a bit to know there are people in other countries who care about you? In that spirit, caring about others enough to risk putting a dent in your happiness is a small price to pay for that happiness.
I think we can safely say that virtually all philosophers choose knowledge over ignorance. Then again, there are many who delve into such esoteric and arguably pointless questions that we might wonder if they've merely turned philosophy into a form of escapism.
It would be interesting to know if philosophers are generally happier than most people. Alan Watts appeared to be a happy guy, while others are clearly less giddy.
I suspect most have no choice but learn how to live with their passion for understanding.
P.S. Regarding your highlighted question about philosophical treatments, see my comment about Aldo Leopold's comment - which I think speaks volumes. I think Alan Watts had something to say about this subject, though it's been so long since I've read his stuff I can't really remember any specifics.
Also, here's a priceless quote from Edward Abbey, an environmental activist who might loosely be regarded as a philosopher:
Has joy any survival value in the operations of evolution? I suspect
that it does; I suspect that the morose and fearful are doomed to
quick extinction. Where there is no joy there can be no courage; and
without courage all other virtues are useless.
Which prompts a question: Instead of limiting yourself to either/or questions regarding Ignorance vs Knowledge, try to look at this thing from various perspectives.
Ah, here's an Alan Watts video you might find interesting, though it doesn't really focus on ignorance vs knowledge. However, it focuses on happiness, which is an integral part of your question.