Most of it, to be honest.
An Alien God is probably up there as the one that gave me the most to think about on a subject I thought I had more or less conceptually nailed.
The Least Convenient Possible World is probably the content that sees the most real-world action with me. Also the "crazy deity is playing a perverted game of blind poker with your eternal soul" line is probably the piece of LW dialogue I find myself wanting to reappropriate the most.
What's still on your mind (in a positive way) a year or more after it was posted?