Raph is king right now. If you haven't seen any of the Raph dodge special lockdowns that Crunan recently shared, you can take a look. My latest run with JJ in 2P has them, some of the recent 1P Raph runs probably will too.

Even without the special cheese, Raph has good damage and high versatility - he's at least average in all areas that really matter.

Splinter has slightly higher single target damage because of the dash special and 2 damage dive kicks, but he'll lag behind Raph in all other areas.