One important aspect of Spaz that people never seem to mention (but use all the time, probably without noticing) is that Spaz can turn around faster than Jazz or Lori by double jumping. I'd go so far as to say that's more useful than higher jumps.

Basically, Jazz and Lori's special moves are sledgehammers made of foam, whereas Spaz' double jump is like a helicopter that shoots homing sharks.