As with all the DA games, you learn the best builds after playing it through a few times. I see a lot of people saying that the dual wielding rogue is your punchy, high octane style, and I fully agree with this. It will be ramped up even further with which specialization you get. For a rogue, if you like AoE damage, you'll want to be an artificer. Otherwise, be an assassin because hidden blades is freaking amazing. (Also, if you can, enchant a weapon or armor to do random hidden blades damage no matter what type of class you are, because... seriously... it's awesome.)

But I also think that the mage has a lot of punchiness to it, again, depending on the type of build you go for. Fade step allows you to zoom around the battlefield (potentially chilling opponents you pass through), mines explode for insane damage, winter's grasp can be modified to do 1000X weapon damage on chilled targets. The specializations are the weakest though. I usually go for knight enchanter for the boost to your barrier.

Of all three games, the most fun I've had with a play style is DAI, Rogue Artificer with the hook and tackle ability. It's... just... BRB, I gotta go build a rogue now.