Team Builds?

I'm nearing the end of Disc 2 and I have enough GFs I can start giving roles to my team now. And I'm having a blast cause, the last few times I played this, I didn't really mess with the junction system too much. I used it enough so I could get through the dungeon I was in and didn't experiment a lot. And I used Zell and Selphie/Rinoa when I could and didn't give the other two much of a chance. So with some experimenting I came up with these roles for my team:

I have Squall as my main DPS. I dump a lot into Strength and Speed. And I gave him counter and I'm having him learn Initiative too.
I have Quistis as a Tank/Support role. I focused on her HP and Vit. I also taught her Recover and Treatment. I have her immune to Berserk and 100% chance to poison with her melee.
I have Irvine as some sort of...sneaky...witch-thief. I'm not to sure what to do with him. His magic is decent so I made him the offensive mage, and I taught him Mug so I get more items.

I was thinking of switching Quistis and Irvine's junction, but having her as a wall between Squall and the enemies seems in character. So how do you build your team?