2-wheel drive 2 electronize 15a, 2 electronize 30a or a sabertooth dual 25a
I'm going to assume you are using two drill motors to provide your drive. The difference between the electronize is the rating or the amount of current that they can handle. The 30A electronize will handle twice the current of the 15A version although the 15A has nice additional processor chip magic in there that means it handles current fine. Basically either one of these controllers will happily handle drill motors all day long. I run 15A (or 12A as they are currently rated if you buy new) in all my machines with no problems even when overvolting. They will happily handle 5 times their rated current for a second or two.

The sabertooth is a more feature packed controller with some nice tweaking available. However it doesn't handle large stall currents or overvolting of motors very well. It should run a 12v drill on 12v source however if you run it at 18v or 24v you may get the magic smoke.

The electronize are single channel meaning you will need one for each motor whereas the sabertooth is a dual channel so two motors can run off one speedo. Cost wise theres not a huge gulf.

To sum up, electronize, not as many features (still give you all you need control wise) but more rugged. Sabertooth, more features, bit more delicate (if you start using it toward its limits).

Various people have their own opinions about controllers like with any hobby. The final decision is up to you.