[Djur]

Tank Treads
Pros:
-Constant platform of support
-Can go halfway off bridge, assuming central or rear center of gravity
-Hard for opponents to push around
-Good traction
Cons:
-Very expensive
-Complex
-Narrow range of uses
-Torque issues

6wd
Pros:
-Good support platform
-Can go halfway off bridge, assuming central or rear center of gravity
-Fast turning
Cons:
-Typically on 4 out of 6 wheels
-Complicated


There are just my team's observations of other teams in the regionals (Boston) over the past few years. We've always stuck with 4wd Mecanum, so no first-hand experience.