Personally, I cant rate one over the other in terms of enjoyability. BUT...
People really forgetting just how big mid to late 99 was for Rock. And this is once he got going as a face. 99, he was laying the groundwork for his success. By 2000, he hit the ceiling. Even when Austin returned Rock was still killing shyt. It wasn't like Austin came back and Rock never recovered or fell off. Once dude made it, he made it. And stayed there.
This goes for Austin in the 97-98 era. He started kicking off in 97 (like Rock did in 99) and by 98 he was THE man who hit the ceiling. 1998 Austin was Rock's 2000.
99 Austin was still hot but he was on the decline as the year progressed. You can tell by some of the select reactions from fans as the year went on. Austin's slight decline (not in a bad way) was when Rock was starting his rise. 99 Austin is like Rocks 2001 (as far as wrestling goes). Rock was declining in 2001 (not in a bad way) but making a transition (into acting) at the same time.
Austin didn't have this good transition to fall back on and thats why today, Rock is regarded as the more popular and successful man now. When wrestling stars to fade, you make a transition to something else. It didn't quite work well for Austin so he was legit juggling part time WWE appearances and trying to get a break outside of the WWE from 2003-today.
Rock, we know how he ended up. Dude just had IT. And it showed. I really don't think people put one over the other these days.
I mean people will have their preference, and thats fine. Its what people chose years ago when it came to Austin/Rock. Some will be bias. Some just flat out hate one over the other. I see it all the time. But in terms of popularity and success, I think we know won that battle.
Its pretty amazing though, that since 99 we STILL have this discussion. Says a lot about the two.