24-105 f4 as part of the 5D MII "kit". Sold it a year later for the 24-70 f2.8 but not because I didn't like it! I was just overlapping zoom distances with other lenses.
I'm no different than most in that it's hard to pick one but recently I've been using my 24-70 2.8L more than the others so now it's my favorite. But I also love the 50 1.2L because it makes me be more creative to get the shot I want.
