I have been horribly unlucky with pack unlocks (playing across three platforms!!) and got only my third overall last night after a pretty fucking incredible duo run through bronze-me as a paltry level 6 soldier and with a level 12 engineer (I still maintain they are the best overall class, but...).
So my veteran pack unlock was the Asari adept. Holy shit on a stick. Fully upgraded stasis bubble, 3 ranks in warp, 2 in asari adept specialty, heavy pistol only +180% recharge rate.
That was the most disgustingly dirty and awesome thing I have done in a game in a long time. During one wave we had an atlas, a phantom, a nemesis, an engineer, and a few randoms charing us (me and two mid teens-an engineer and vanguard). One of them took out the atlas with a missile, and I chain stasised every single fucking enemy on the map as we slaughtered them. At one point I solo'd a target wave running around like a psycho putting everyone in stasis lock so I could hit the final target and move on.
It is ridiculously, gloriously overpowered. I can't even imagine how terrifying that would be on an Asari Vanguard with charge and a pistol only build.
I will say that I still, after all that, think a fully upgraded engineer is the best class in the game, especially for the challenges on silver and gold.
It's funny how a coop horde mode (I have barely played any horde in Gears, though I like the multiplayer) has completely and totally enthralled me. I don't know if it is the universe or setting or the fact that it is just moreMass Effect, but I love it!