please none of them, and i say that with neutral feelings towards MK, i also don't want any street fighter characters either. for one Toro has moves from certain characters movesets in those games it would just be bad to make Toro's moveset with moves from those characters then to actually add one in the futre.
Wait hold on... What do you mean Toro has moves from those games...? Name one thing Toro and say Scorpion would have in common. :l
Toro's neutral triangle chain attack and Toro's forward triangle dash with the bones coming from the ground. the down triangle is like Noob Saibot's disappear and reappear from above attack.
Why not Shang Tsung? He'd be good to represent a lot of the other characters. they can just give him his transformation ability.
Edit: Let me clearify, I don't mean just make his entire moveset be just transforming into different characters, he can have his normal moves on square, triangle and circle, but here's how I think his transformations should work, pressing nuetral circle puts him in a stance for a few seconds, during that stance you can either tap circle again, press up circle, down, left, or right circle and each command will give you a different character transformation
Nuetral circle would be Liu Kang
Left circle would be Kitana
Right circle would be Raiden
Down circle would be Sub-Zero
And up circle would be either Scorpion or Johnny Cage.
There you go, 6 Mortal Kombat characters in 1 without wasting character space, and it wouldn't even have to be the same as in Mortal Kombat where you only play as the transformation for a short time, just tap nuetral circle again to transform back.