On balance, I would think the ST library is good. Well documented, and good naming convention and easy to use as well. They don't have as many examples to get people started, however. ST's hardware also has a lot of resources but aren't as rich as TI's - rather than having identical well-featured peripherals, they have multiple timers each with slightly different twist.
NXP, like TI, also has good hardware and a long history. Their chips, however, are not as feature rich as TI's.
The luminary library was actually good for its time but it is becoming a baggage for TI now, in my view.