I have intense respect for the history of gcc, but everything about using it screams that it's stuck in the past.
LLVM has a lot of problems, but it feels significantly more modern.
I do wish we had a "new LLVM" doing to LLVM what it did to gcc. Just because it's better doesn't mean it's perfect.
Basically, you can respect history while also being honest about the current state of things. But also, doing so requires you to care primarily about things like ease of use, rather than things like licenses. For some people, they care about licenses first, usability second.
Their IR is a mess. So a "new LLVM" ought to start by nailing down the IR.
And as a bonus, seems to me a nailed down IR actually is that portable assembly language the C people keep telling us is what they wanted. Most of them don't actually want that and won't thank you - but if even 1% of the "I need a portable assembler" crowd actually did want a portable assembler they're a large volume of customers from day one.
Having tried writing plugins for both, I very much prefer GCC's codebase. You have to adapt to its quirks, but at least it won't pull the rug from under your feet gratuitously. There's a reason every major project ends up embedding a years-old copy of LLVM rather than just using the system version.
If you're ignoring the API and writing IR directly there are advantages to LLVM though.
Honestly, I love that both exist with their respective world views.
I for sure don't want to suggest that anyone who loves gcc shouldn't be working on what they love. More compilers are a good thing, generally. Just trying to say why I have a preference.