Jean Grey is more iconic than she is interesting.
Cable is inherently too messy of a character and has only been interesting in 5% of the comics he's appeared in. The good does not outweigh the bad.
Laura was at her worst in the 'New X-Men' series and has benefitted from her distancing herself from that generation.
Having potential <> being a good character
Moonstar is a great character with awful mutant powers and I don't think she'll ever ascend to the heights she deserves because of it unless they make her primarily a Thor character / play up her Valkyrie abilities
People only like Magma for her powers. She is the worst, but she will never make those asinine 'worst X-Men lists' because she is molten lava with breasts.
Apocalypse was a crap character until the 'Arrako' stuff came out.
Rogue should be an Avenger full-time.
The only pre-Claremont X-Men I would keep on the roster are Storm, Cyclops, Wolverine, Nightcrawler, Kate, and Magneto. The rest should be retired / fulfill other roles. The aforementioned six should all age, evolve, and foster the growth of other characters.
Multiple Man is incredibly annoying and kind of a perv.