Its a matter of preference, I think. I was only able to play UT growing up, thanks to its software renderer, and finally played Q3 (Quake Live) in college.
Q3 is more minimalist, which makes competitive play more interesting. Q3 has also maintained a competitive scene to this day where UTs seems to have fizzled out.
Doom (2016) was released after Carmack left, but it's one of the best shooters they've made.