Sabertooth's (Saberteeth?) are very nice controllers. Small, compact, silent, feature full (fail safe, lithium mode, mixing built in) and a good price.
But for some reason they do just seem to break down for no good reason... Some people have never had a problem, whereas other like myself have had them fail without the robot having ever been in combat!
On the plus side their customer service is very good and are very willing to help/replace faulty good. On the downside they are based in America so postage takes a while plus the USPS loses pretty much every package it has to deal with!

What motors do you plan on using?

The 12amp model is about as common as the 25amp one in FWs, it all depends what sort of current you think you'll draw, which can be tricky to figure out.
25amp is a lot, so go for the bigger one if you want to be safe. You should fuse the expensive parts of your robot anyway if the current does go wild for any reason.