Voted Broken Steel. Such a good DLC.
Operation Anchorage was good, but once I'd done the mission it felt finished. Although the Chinese Stealth Suit is fucking amazing.
Point Lookout was a disappointment. It was just so boring! The atmosphere didn't get me, not like the main world did. Again, it felt like there was nothing else to do there after the mission.
Mothership Zeta was a mess. I found it more a chore trying to kill the aliens with the shiny shields, they were impervious to EVERYTHING! Hell, I even used up my supply of mini nukes to deal with them!
The story wasn't that great. The girl was annoying as anything. Although the interactions on the ship were pretty good (making Raiders and radscorpions fight) and the fight with the other ship.
I never got Broken Steel, so it could be the greatest thing ever and I wouldn't know.
So yeah, Broken Steel was the only DLC that I felt was worth the money.