Ein was my main and i was SS ranked with him in Ultimate and 4 so i know your pain lol. I've been giving Mila a go, but i use to play Tina in 4 also. Her mix up is nice, and you can grab cancel a lot of her moves.
If you aren't a fan of grapplers, i'd say give Jahn Lee a shot. Dragon Gunner is OP.
Hayate has some of Eins moves too. Guess he still remembers some karate.