Well, you can go with Corr, they're pretty well off on their own great burst dmg. I went with Fire Blast/Pain Dom... and he's yet to disappoint.
MM however, you have to keep in mind the pros and cons of all the pets...
Bots, AWESOME dmg and one of them is a personal support-char to you and the other minions... BUT The higher the level the more the knock back powers start to come into play... if you don't mind knocking back your targets... than go with this...
Thugs, Great overall dmg if you are going to rely heavily on your pets, these be the way to go... though, their resistance to dmg taken is on the suckie side... properly slotted and buffed from pain, and that could be bypassed.
All other mm primaries would require you to pick up more pain powers than pet powers, probably requiring you to sacrifice much needed powers on either side of the set.
IMO, I would honestly stick with Thugs, because their only downside would be virtually gone due to your pain powers.