1) Arkham Knight - mainly because it's a highly maneuverable tank in addition to being a car
2) Batman/Batman Returns - so iconic
3) Batman Beyond - also because of it's high functionality and versatility
You may want to consider holding out a little longer, Acetoyz is doing a version as well. I have faith that theirs will be the best, but if not, I'll probably go with VS
If they had no intention of releasing this, I don't think they'd keep showing it at all the conventions. I'm thinking they're waiting for the formal announcement of the next Arkham game (rumored to be Arkham Legacy).
Hopefully we can get some of the other characters shown (namely Prime). I already pre-ordered this, and saw an advanced screening Sunday night. There aren't too many other cameos aside from what's shown in the trailers, but any G1 fan won't be disappointed.