Yang. Nobody even comes close. I still say playing all or almost all center ball is handicapping yourself, but with Yang that simply wasn't true. He overcame it with pure talent. He got into trouble a couple of times, because of it, and quite unnecessarily IMO, but with his record, who am I to argue with him?
I'm sorry, but Sigel and Hall do not figure into it. Sigel used a lot of outside english in his game, and also other types of sidespin. I modeled my straight pool game on his, as best I could from studying his patterns on video. Trust me, he played sidespin quite a lot. Buddy Hall invented "The Clock System" for crying out loud! I do agree that he's the best position player of all time. If you think I'm full of it, then simply watch the old Accu-Stats tapes, from back when Grady was still around. Back then, the commentators discussed shots in detail with english used, Hall and Sigel both commentated. Notice what english they recommend. Not all center, that's for sure! However, they were products of their times...
Modern tables have completely changed the way in which the game is being played. Modern rails are much faster, which not only makes english less necessary to get around, but also causes the rails to bank short and the english not to grab properly. The game will get more and more center ball oriented, this will be especially true if the chineese 8 ball tables catch on. These have snooker cushions, which react completely differently to english. I do not like these developments, I find them to make the game more boring and less knowledge oriented, with the focus more on ball pocketing than position. Several types of shots have gone completely out of use. For instance, on the tables in my club, it is close to impossible to "kill" the cueball in the corner (2 rails). I haven't ever seen that shot being made or even attempted since the "modern" cushions were installed, because there is no point. The cushions just throw the cueball out too hard and fast and the kill english will only alter the angle slightly rather than kill the ball. Several other types of shots are going out of use as well, mostly shots where the cueball glides along the cushion with spin. It comes off the cushion so hot that there is no time for the spin to grab. I guess you could say that it makes speed control more important, and the tighter pockets certainly makes pocketing balls more difficult. So pool, traditionally somewhere in between carom and snooker, has moved a lot closer to snooker. Heck, many of the carom type diamond system simply do not work properly, or need huge adjustments on modern pool tables. I for one, do not like it.
That being said, pros use sidespin. Even Yang does, albeit less than many others.