A Jihaxus toy that actualy looks like Jihaxus would be my vote. Yes I know he technicaly has a toy, but It doesn't look like him. I may as well just call some random TF tank toy Impactor.

Impactor would be my second choice, as long as he came with an alternative zombie Impactor parts or limited ed zombie version.

I'd also like to see Hook, Line and Sinker, a Deathbringer and Leige Maximo, though they would probably end up some sort of action figure rather than a TF.