This is my first year NOT working with wood for a drive base, and I must say I don't really have a favorite.
Wood is, for the most part, easier to work with. With little to no resources you can cook up a pretty solid base in less than a day. Electronics mount up nicely to it, and you can even give it a
slick automotive paint job. Beyond that, with the proper reinforcement you can slam the thing into walls all day and not have to worry about it bending or breaking.
Aluminum is a bit lighter, and more customizable. You can get some pretty unique shapes and work motor mounts directly into your parts.
I don't really see a big difference in terms of strength (for the purpose of a drive base) between wood and aluminum. Wood has the tendency to gouge, which isnt all that pretty, but for the most part it holds up quite well.
So, I guess its all a matter of personal preference and experience. YMTC.