First of all, if you are *just* looking for damage, the class may not make you happy. Second of all, if you still wanna squeeze the class for damage, I suggest either Fire Control or Plant Control. Fire Comes with more damage out of the box (if you slot Bonfire with a knockback to knockdown Enhancer), but plant control quickly catches up in endgame and IMHO offers superior control with its Seeds of Confusion). Gravity is also something to consider, as it has a high damage single target attack in the primary pool, something the other sets seem to be lacking.
With Secondaries, it gets a lot more tricky. Again, I'd say Fire comes out on top damage-wise (just a feeling though, I have no hard numbers to back it up), but offers not much else. Martial is a bit wonky with all those shuriken attacks, but its a pretty cool looking, area focused set. However, none of the sets (at least of those I have tried) are really bad. All of them have some cool abilities (Earth with its stone mallet, Electric with its energy drains, Savage with Spot Prey, etc.) and are still pretty decent in damage.
tl;dr: Look for what suits you best instead of the numbers. I found this to be truer with Dominators than any other Archetype.