Sakura beats 'em all! She's got speed, anti-air, projectiles, a high jumping attack, and a projectile stopping running Cherry blossom punch (that's what it's translated into). Plus, she looks prettier. In SFA2 (her debut), she was pretty good. Her Running Dragon was a 1-6 hitter. Her fireball could be increased in strength (even though it loses range), and her shun pu kyaku was strong. She also had that Jumping thing that attacked with a small head aiming attack that made her bounce off the opponent when she connects. Her Supers where great too, Shinku Haduken (medium hight), Midare Zakura (low-high), and Haru Ichiban (low only). She had great attack types for each type of terrain. In MvsSF, She fires hadukens horizantally, in the air too, but they take a LOT of damage compared to other projectiles. The Hadukens are good for anti-air, and keep away games too. Her Shououken is great in the air or on the ground. She can use it in the air to dodge, not fall in front of the enemy, or to attack. On the ground, she can use it to avoid jump-in's, or stop jump-ins, attack regularly, avoid Hulk's Gamma Crush (Which is fun to do...), and it's easy to combo into. Her shun pu kyaku can go really high and far fast. It's good for doging while attacking. It can also be used in a combo, and cause the little bit of extra damge you might need. Her Shinku-Haduken causes great chipping damage, and can connect if someones really close, or is jumping in. Best of all, barely any start up time! Her Midare Zakura is great for damage, and can connect if an opponent is in the air. If blocked, though, she bounces forward, but she can still attack, and catch the opponent off gaurd. Her Haru ichiban is good for damage as well, even though it goes straight into the air. It can connect any time during the attack, and when she falls down, she cannot attack, but she can still block (unless she connected).It can be used for dodging things, like Ryu's Shinku Haduken, or Gambit's Mega obtic blasts. All in all, Sakura could kick there asses if played well. Sakura rocks! ^-^

Actually
Wolverine will kick almost anyone's ass in the Capcom vs. series. This started out as a Ryu vs. Ken post, but since you brought it up, there are others that are good, too.
Wolverine's weapon X is one of the most powerful supers in the game, and will go through any projectile (even Ryu's "big one" :biggrin:). It also comes out lightning fast, virtually teleporting him across the screen. His dash is one of the most effective in the game, and he's in your face and starting a combo before you even knew what hit you. Berserker barrage X also does excellent damage when you put it into a combo, and it initiates the "flying screen," giving you a chance for even more hits. Wolverine's drill claw has excellent recovery time, can be done in the air (even to change direction mid-flight), and can be done in any direction. His slide can go under anyone's projectile (except for Ryu's :( ). His fierce throw is also very difficult to tech hit out of, and he can strong throw in the air. Overall, I would have to say that Wolverine is perhaps the easiest out of all the characters to do combos with. Unfortunately, that also makes ppl refer to him as a "button-smasher" character, although I disagree.