Alright let's start this list already.
There's gonna be a "Pros" list and a "Cons" list.
These are entirely subjective and my personal opinion, you might have different opinions.
Some of these "Cons" aren't even that bad, just simply not my thing.
Curseforge's own launcher works perfectly fine. It has direct install buttons from the browser to the app, so if that's important to you then go ahead and use it.
MultiMC is an open-source launcher aimed towards people that imply don't enjoy using Curseforge for one reason or another.
I don't personally use it. No hate to the devs, but all the drama stopped me from using it.
You can use it if you want, just know that none of us care for it.
Prism Launcher is also a fork of MultiMC, made by the old team of PolyMC, after all the drama.