My favorite is the Very Good ending. I just take immersive games like this so personally. After being educated through the PA system, audio diaries, and some thought, I didn't want Lamb to die. Perhaps our message of hope and love will make a mother out of her yet. I'm a sucker for kids, too.
I just can't bring myself to harvest the Little Sisters.
When Sinclair tells me the Little Sisters aren't human anymore, I couldn't believe it. I never played Bioshock, but I knew the general storyline and outcome. (I'm going to play it soon-- I'm not spoiling
all the characters and stuff for myself.) Plus, I saw into the room with Brigid Tennenbaum. Those were clearly little girls in there. I was glad later when through diaries I realized how much of a shark Sinclair really was at heart, despite his genuine want to help you (even if it was in order to help himself up until the end.)