I would also add Bishop, X-23 and can`t choose between Psylocke/Sage/Frenzy.
Frenzy. If I had to choose.
Ideally; Havok, Polaris, Frenzy, Gambit, Bishop and Magik
or Havok, Psylocke, Angel, Gambit, Bishop, Magik and Frenzy
The art of forming a team isn't just throwing your favorites in a bowl and tossing vigorously. Each member needs at least a function or connection to someone else on the team. But in either group you have a theme of redemption and/or darkness. Not to mention, tap into characters with fan followings. If I could I try to sneak Dazzler or Emma in their and then you'll be sure to make this book a top Marvel seller. And not make this a X-Force team, an X-Men team with an ongoing theme, not just a single mission.