He's not my style in the least but in referencing mainstream he's about as big as you can get without mentioning another Canadian who frequently tops the charts, just gotta point that out. I do think Houston's rep though is kind of frozen in the past, in that I agree there's not a lot of newcomers (from what I can tell) going to the top via Houston. Latest big name from Texas I can see is Post Malone and he reps 214.
Oh, definitely agree, I just can't stand him at all and have to express it at all times. Drake thinking he could rap on June 27 is borderline blasphemous and if Pimp C didn't want to do Big Pimpin' with Jay-Z, there's zero chance he would be associated with Drake.
I haven't really kept up with rap in a few years so I'll take your word for it but yeah I haven't heard of anyone really either.
edit: I can point to Houston influence in so much music but yeah definitely dont get its due props.