While there are games that have been great continuations of series that had their beginnings in previous generations, this gen has seen the rise of some amazing trilogies.
So the criteria is pretty clear for what qualified entry into the poll;
* 3 games to the primary series, not including spin-offs, prequels, etc...
* beginning and concluding in this generation.
I still haven't played AC3, but my experiences with the series up to Revelations have been a joy. I also think Gears of War really brought something to the shooter table, and would like the chance to play Uncharted some day. But the trilogy I pick as the best of this gen will probably surprise you.
Yeahhhhh, it's Mass Effect, for it's rich universe, diverse races, memorable characters and some epic set pieces. But most of all for having such strong continuity across a trilogy. Unlike other series, you don't play some tangent character loosely connected to the one you played in the first game, running their own parallel path to the overall story. Each instalment is a direct continuation of the story of your character, personalized to your design along the entire journey. And that's what a trilogy should be.
But now it's time to vote and have your say, System Warriors :)