My 'ideal' party is usually:

Tank: Alistair, always. Guy can shrug off damage so adorkably.
DPS: My Dual Dagger Female Cousland fitted this spot.
Support: Wynne, typically, but Morrigan could adequately fulfil this role too.
2nd DPS: Anyone else. Another offensive Warrior, Leliana or the unused Mage. Zevran was used the least in this role.


Basically, whatever role I filled, I tended to use the character who also filled that role less. In DA:II, I played a Fem!Snark!Hawke, who wielded a two-hander. Fenris, while a great guy, didn't get so much of a look in combat. Playing the tank is probably the worst choice you can make. Alistair, Aveline and Blackwall all fulfil the role of tank remarkably. Having your Warden also be a tank is rather a redundant choice.

EDIT:

Quote Originally Posted by Spuuky View Post
Anyone but Alistair is fine, what a loser he is. Sorry buddy, I can see that you're a frail little flower using self-deprecation to hide from your shame, but it doesn't actually make me respect you as a human being.
You dislike Alistair?!