I've bought Lair of the Shadow Broker and Overlord. If it showed me anything, it's that Mass Effect, particularly Mass Effect 2 because of the more shallow RPG elements, lives and dies by my investment to the narrative.
Overlord was definitely the 'best' mechanically, and I did have fun shooting things to cool music, but I sort of did the whole thing half awake, and the end narrative punch didn't really work for me, and there we only so many samey combat encounters I could do before I got kind of bored (same with parts of LoTSB).
LotSB though, as one of the few people that really liked Liara from ME1, the writing was very mature aside from the comical dialogue during combat, and I ended up I loving it.