I can't finish the game as anyone but a Mage.

First off, you've been talking about literally everything else but the base damage of spells throughout this conversation. Nobody can read your mind. If that's what it comes down to for you then say that, and don't whine at people for not extrapolating it from you talking about something completely different.

For future reference, "I feel like spells do too much damage and that makes mage playthroughs a bit too easy compared to the other classes. And that's a shame." would be sufficient to express that viewpoint clearly. And while I haven't played a mage recently enough to say for sure, I won't deny that there might be something to that, at least in Origins.

Second, I didn't say you blame mages, please read the full sentence before biting someone's head off. It sounded like you blamed their "OP"ness on the fact that mages suddenly learn a lot of spells on the journey, since that's what you were complaining about. Which doesn't seem logical. That's all I said.

Now we both know what the other was trying to say. That's great. Let's call that a successful discussion.

Well, back on topic, again.
Let's see if it sticks this time.

I've tried Warrior runs, but Aveline just outshines in that role.
I've tried Rogue runs, but unless you go Dual-Dagger you have Varric.
Which leaves you lacking a mage, which means either Merril (who can't heal) or Anders.

To be fair, I prefer Mage in Dragon Age, but this game seems more "designed" for a mage character.

The combination of my Archer Hawke,Merrill, and Aveline make needing a healing mage unnecessary.

Yeah I think those 3 aer the ones I tend to use most as wel when I play DA2. Sometimes I do switch out Aveline for Fenris  or Isabella for Fenris but generally onl yfor as yone of the tougher fights where I might need 2 warriors instead of 1.