I think the spirit figures are awesome, and there are certainly a few more that would be appropriate. And since Mattel has outright TOLD US that they would be able to reduce the cost of the figures if we were willing to accept less paint-apps, there should be no reason for these figures to cost as much as regular figures (also because no new tooling would be involved). I'd be up for all the main cast:
King Grayskull (in a different color so the original retains its exclusivity)
He-Man (and maybe a slime pit version, even though I'm not dying for one, I know a lot of people are)
She-Ra
Skeletor
He-Ro
Teela or Evil-Lyn
another female for sure, but I'm not sure who; we already have TOD Sorceress, so I kinda feel like she's covered, and Evil-Lyn makes more sense (to me) but Teela would give people a chance to paint her and make their own of the regular version!