Shotos all around, depending on what you want to emphasize:
Akuma: Hit and run style. Fragile, highly mobile, excellent control over the pace of the match. Great, if complex okizeme. Good control tools at far ranges, but lack payoffs - needs to create and opening and go in. High combo damage up close on standing opponents, setups loop. Poor stun output. Akuma is a slippery bugger and generally hard to pin down.
Ryu: Mr. Solid. Basic, a bit defensively minded. Good midscreen space control, can win better via zoning because the zoning and esp. AA game do good damage. Not a mixup character. High combo damage, good corner carry, decent stun output. Good burst damage from footsies.
Ken: A bit less solid than Ryu, but a good mixup game. Not a bursty character, so a Ken player needs consistency. Step kick is amazing, his sweep is a good footsie tool, but not a punisher like Ryu’s/Akuma’s extremely fast sweeps.
Oni: All around solid character like the rest, but a bit weaker in the neutral game. Mixups galore, up close combo damage and corner carry are monstrous. The kind of character that’s kind of iffy, but if you have a read, someone better be writing their testament. Very bursty, long combos type character. If you like cancels, Oni’s combos are unusually cancel-heavy for SF4.
Evil Ryu: Lacks the traditional shoto specialty of a long, low poke with fast startup. In return, is an otherwise very solid character, those low pokes have amazing range and, uh… Evil Ryu deals the most damage in the game, and it’s not a contest. His stun output is also high. So less midrange control in return for a good boost at far range and upclose. Long combos, but more link-heavy in SF4 style.
Sakura: Is a dick. Give the opponent a coffee as courtesy while you’re hammering away at your combo, and apologize to the TOs when the next round starts in half a year.