for Ken:

Gief -- good gracious, I feel helpless in this one. your footsies have to be perfect, and one mistake puts you in a cr. jab / meaty headbutt / ex SPD / air SPD vortex if he lands a knockdown.

Mika -- not even sure what's safe and unsafe with her yet. she has a lot of mix-ups into command throws and a misplaced fireball puts you in a world of hurt. oh yeah, if you're in the corner prepare to lose 50 percent life.

Nash -- I've gotten a lot better at this one (cr. hp beats moonsault at most distances and easier to react to than mp srk) but a comparably skilled Nash player is going to beat me every time. his block strings and buttons in close seem strong against Ken.

Bison -- fuck this guy! I know top players are saying he's not as good as first thought, but if he has meter he's fucking brutal.

I haven't played many good Lauras or Sims. Ken is OK in mirrors because most of them are flowchart with a heavy dash of YOLO. I played an Ultra Bronze Ken that was doing random fullscreen hard tatsus.

Ryu is even because of his damage potential but again, at my level (1000-1300 LP) you can beat 70 percent of them with simple anti-airs and wake-up shoryuken baits. plus it's the matchup I've played the most.

Cammy and Karins do some annoying things, but I think you have to be really good to maximize their advantages. Necallis can usually be blocked and punished when they go for stuff like half-screen disc guidance, or spam HK on rhythm. I do get wrecked by Vegas but don't play them much. Chun is super good but most people under Silver can't do all her dirty stuff.