Deadpool's regenerative abilities used to put him at the top, but they've been fluctuating so badly I don't really know where he is now. I hope Nicieza resolves this at some point.
Ikaris, another winged mutant, one of Cannonball's siblings who appears in the New X-Men book has a healing factor.
Blazing Skull from New Invaders, although I'm not sure if you'd call it a healing factor. He's immortal, and as such can feel pain, but any physical damage doesn't do anything. Although he was just beheaded, so we'll have to see how that works out.
When Gambit's powers were amped way up awhile back in his previous ongoing series, somehow he used his powers to heal himself.
Agent X has a copy of Deadpool's regenerative abilities.
Beast also has a healing factor. His first time in fury form he had a massive healing factor that would put Wolvy to shame, then he turned human again, then into blue fury form with a healing factor, but nothing to really write home about, and now in his lion form, I'm guessing it's been amped up a bit, but we've haven't really seen much of it.
Ok, how about this. Let's not include the cosmic beings, they all have some hind of healing factor. Let's not include anyone from DC or other dimensions either. Here is the updated(?) list.
1. Dead Girl
2. Hulk/Abomination
3. Wolverine/She-Hulk(?)
4. Sabretooth
5. Native(?)
6. Wildchild(?)
7. Deadpool/Agent X
8. Archangel
9. Beast
10. Icarus