Depends on the game. The only pure SF game that Ken has been by consensus better is 3rd Strike (in which he is significantly better). Ironically in AE2012 they are probably close to equal objectively on the tier list, but Ryu is more balanced and popular among some prominent character loyalists and so tends to get the nod (there's been no truly great/dominant Ken player, and he has a reputation as scrubby in this game). MOV, one of the GOAT 3rd Strike players, played Ken at EVO and there's an extremely strong player from High Desert who got Top 32 using him (frequently plays at WNF).
I main Sakura myself (who is top tier herself and potentially better than both), so I couldn't really care less