i drive myself crazy with wheel shapes all the time. I personally think the conical sidewalls are not as aesthetically pleasing as the classics, or even the radials...
anyways, the classics are already a pretty wide wheel to begin with and if you skate a set of em long enough, the riding surface gets to be just about as wide as a conical shape, and then you have the more attractive sidewalls.
i dunno. i'm still influenced heavily by whomever's part(s) i'm watching at the moment. if i'm watching more recent skate parts (or even AVE), I tend to want to throw on some conicals, but if im watching older stuff then I tend to want to throw on some classics.