The new 3.X day music is very good, probably my new favorite track would be 3.1's day combat. My 2nd favorite is still the formicarium combat, though, and 1.2 ambient and combat would have to be my 3rd and 4th.
Mine is still 1.2 - I love the plucked strings and how thematic and evocative it is of spiders. A very close 2nd though is the militaristic combat music from 3.2, particularly when it gets to the choir stuff. I'm a sucker for some good chorals.