The best episode/game/movie/whatever in most trilogies is usually the 2nd. Mass Effect is no different. The 3rd failed in many ways (with a gaming sin being the biggest) and while I love the series in itself I don't want there to be another Mass Effect game.
As Yahtzee put it, where do they go from total annihilation of everyone in the universe? I'd kind of prefer a new IP from the same developers.
Hmm, pie.