Hey, what a coincidence. I'm playing through this game right now, and nearly finished it again. As nordlead posted above me, you really can't go wrong with a team of interlocking supports between Ike, Soren, and Oscar. But you forgot to add Kieran to the mix as well! I think that both Ike and Oscar are getting 40% or more to their avoid rating - that's a nearly untouchable front line.
By the end of this game, it really doesn't matter all that much which characters you pick, since you can create a godly team quite easily. I ended up with:
Ike
Soren
Oscar
Kieran
Boyd
Rolf
Mia
Nephenee
Jill
Gatrie
Volke
Rhys
Even on the American "Difficult" setting, this game is still one of the easier Fire Emblems. It's a ton of fun to play regardless though.
End of 2008 totals: Wii 42m, 360 24m, PS3 18.5m (made Jan. 4, 2008)