GCC is more spaghetti than Clang, less modular. But yeah, it's mostly political/business/legal related. A lot of people hate copyleft with a passion like Apple and Google, who hire lots of people to work on LLVM.
The idea seems to be that LLVM will eventually catch up to GCC on quality of generated code.
Google didn't move to clang/llvm because they hate copyleft. They moved because people who work on compilers prefer to work on clang/llvm, and if you have a compiler group you need to keep them happy.
It's probably also true that the FSF is more of a pain to work with than absolutely necessary — they want copyright assignment, have some abhorrent code style, and still insist on tracking useless diff summaries in ChangeLog files long after the invention of RCS systems.
GCC is more spaghetti than Clang, less modular. But yeah, it's mostly political/business/legal related. A lot of people hate copyleft with a passion like Apple and Google, who hire lots of people to work on LLVM.
The idea seems to be that LLVM will eventually catch up to GCC on quality of generated code.