I liked the way it was decided during the Utopia period.
A core team with leaders (which consisting core members) Who then lead, or co-lead teams.
Looking at popularity I would put in that core team: Cyclops, Wolverine, Storm, Psylocke, Rogue, Havok and Jean. Added with Cannonball, Sunspot, or Moonstar.
Let Jean and Namor have a team - Red II
Rogue and Gambit lead a Young X-Men team
Wolverine and Iceman on a new X-Force
Psylocke and Archangel on Excalibur
Cyclops and Storm co lead Uncanny
Havok and Polaris on X-Factor
Sunspot, Dani or Sam on Newer Mutants