Favorite trilogy: Mass Effect. 1 was awesome, 2 was arguably better, 3 started off good but fell apart at the end.
Favorite 3 from a series: Metal Gear Solid, MGS3 Snake Eater, MGS4 Guns of the Patriots. MGS is the first game I ever finished in one day, I was hooked and couldn’t stop playing. Then MGS Sons of Liberty came out and switching from Snake to Raiden pissed me off more than it should have. Snake Eater is viewed by most Metal Gear fans as the best in the series (I still lean towards 1), and while those same fans like to pick 4 apart, it was a satisfying ending to the saga for me (only for Metal Gear Solid V to come out later).