Wait wait wait. I gotta get in on this streetfighter thing.
First, Kens over-reliance on the dragon punch is his weakness. Notice it goes further horizontally then Ryu's but not near as high vertically.
Ken is a pick character. he pokes at his opponents and relies on combo damage. Note how his spin kick doesnt do knockdown damage which usually results in ken getting slammed.
Ryu has the faster taller uppercut, a better fireball and a spinkick that clears the opponent and allows you to regroup. Add in the excellent sidekick move from SF3 and the unblockable fireball special and you have the best character short of Akuma or Shin Akuma.
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"When I let Go of who I am, I become who I might be."
Lao Tzu