I am happier when I see copyleft but let’s be honest, I would contribute to an interesting, useful project regardless of their choice between MIT and GPL. Same for companies: some prefer MIT, but there is no way they are not going to contribute to the Linux Kernel just because of copyleft. So bottom line is: make something that people enjoy/find useful and see contributors flocking.

CLAs are a different matter: I do not contribute to projects which ask you to assign them copyright unless I 100% trust the organisation behind them.

I'm just me, but I'd rather contribute to GPL projects than MIT ones, all else being equal.

That said, I've not really done any significant amount of "contributing" to other folks' projects. Mostly the open source code I publish is my own single-handed thing. So far, anyway. (Maybe I don't play well with others. 🤔 )

I don't think it matters if you target hobbyists. But maybe for commercial use. Or if it's a library. Or if you're within a specific ecosystem like Android where people mostly have agreed on one specific license.

GPL is the only good license out there. MIT just leaves too many opportunities for abuse because corporations won't ever do what is in the best interest of humanity.

GPL with a paid commercial option for companies that need closed source derivatives.