I have no loyalties as of yet, but I used:
Ernie Ball Bass Slinky (5 months) -- Good for the price! Loved 'em
Ernie Ball Flats Group III (5 months) -- Nice thump, but you can't play chili peppers funk so they had to go
Rotosound 66s (3 months) -- Ehhhhh, not as nice in my opinion as the ernies or d'addarios
D'addario XLs 45-100 (October-Now) -- I love these things! Fantastic strings, I can see what all the hype was about.
I've got a set of Thomastik-Infeld Jazz Rounds on my bed right now, gonna suit up my bass with 'em after I sling in some new electronics in about a week and a half.