It depends a lot on what sort of resources you have. We have easy access to a Tormach pCNC 1100 in our room on campus, and less easy access to a sheet metal shop with laser cutting capability. The choice is simple; we do a cantilevered style live axle drive train with chain tensioning that works by swapping in different sized idler sprockets between our wheels. We CNC the side members of our drivetrain and the bumper standoffs out of tube (2"x1" generally, sometimes 1.5"x1" if we can get away with it).
Since reliability is, above all else, most important to us, we run direct drive to the wheels. One more chain run is one more chain run to tension, and one additional point of failure that could cripple an entire side of the drivetrain. We achieved our desired reduction entirely through the design of custom gearboxes and machining the side plates on our CNC (not a difficult endeavor with an in house machine). 16 ft/sec served us well this year.
If you have access to sheet metal resources, I would consider making something sweet and lightweight like Team 33's WASP drive; the use of the bumper rules to allow a lighter weight frame but heavier duty bumpers is very cool.