My list changes from era to era and from recent readings so it's ever changing and never permanent. Though some are mainstays.
1) Rogue
2) Doctor Strange
3) Hulk (Bruce Banner)
4)Clint Barton Hawkeye
5) Jean Grey
6) Spider-Man (Peter Parker)
7) Songbird
8) Kate Bishop
9)Cassie Lang/Stature
10) Wiccan
Characters who have been on my 10 list frequently: Illyana/Magik, Rahne/Wolfsbane, Hulkling, Moonstone, Nightcrawler, Steve Rogers Cap, Scott Lang, Hank Pym, Wanda, X-23, Valkyrie (Brunhilde) Atlas, Jolt, Ben Grimm, Dr. Doom, She-Hulk, Janet Van Dyne, Colossus, Baron Zemo.
Edit: Crud, I forgot to add Power Pack! Marvel and their millions of characters lol.