I guess overcoming one's weaknesses takes a long time. Vega, Ken, and Ryu are at the top of that list for me.
I notice that Chun's standing RH tends to bitchslap incoming shoto roundhouses. Otherwise there's the standing MP if they're closer, but it's unreliable. Blocking on wakeup seems to be the best, it's just a tough trap to get out of, and basically a guessing game, esp. with ken's knee.
And also her new SBK is a better AA than I had first thought.
And SF4 chun is going to have a tough time with people who jump in from what I've been reading. Still seems to have beastly normals, though. I've always liked that about her.