Overall I would say the Jaguar was under developed, it had far more power than what we seen but was hampered by Atari and bad developers. 32x comes close but seeing as it was a abortion of a add-on to begin with...I dont see it ranking as high as the Jag.
N64 we saw plenty of. CDs would have helped sure, but not immensely so if you ask me.
N64 DD - same as 32x.
Sega CD - could of been utilized better but still, it was for the most JUST a CD drive add on with scaling and rotation tacked on [plus a faster CPU]. A higher color pallete should have been mandatory from the start...That would have made all the difference.
Sega Saturn - Close to the Jaguar. It had 7 or more processors in it...It died to early, a great dev team could have done wonders with it though Virtua Fighter 2 showed it off.