In order for an IPA....
1) US-05 --cheap, easy, fast. (I keep about 8 packs on hand for nearly any type of beer).
2) White Labs 007 --Dry English Ale---if I have some (which I currently don't)
3) Wyeast 1764-- Pacman--made a stone ruination clone and hit my gravity numbers with it--attenuates at around 80-82% for me--harvested some of this and will use again soon.