After building and using a couple of mobile bases recently, I'll never again have any mobile base with anything smaller than 4" wheels, easy to lock and unlock without bending over locks, and ball bearing swivels. 5" and 6" are not too big for heavy tools. The 4" ones are for light tools like a drill press. I'd put a cabinet saw on 5" wheels.
For a tablesaw, consider how you're going to mount an overhead dust arm.