I'm a member of several different bourbon sites, and this question has come up before elsewhere. Most times, I've been half kidding and half serious when I reply with, "The one in my hand." I say half kidding/serious, because I believe that ones tastes change over time. At least mine does. What I really like today, I might not care as much for six months down the road. That being said.....
My two favorite "categories" of bourbon are wheaters and BIB's. Love 'em both, with the wheaters coming out on top by a narrow margin. Weller 12 was the first bourbon that turned my head and made me go "Hmmmmm." I'd have to say that my favorite semi-regular/everyday pour would be Weller 12. My favorite "special" pour would be the 2007 WLW. I switch things up every so often, but it seems I always come back around to my beloved Wellers. YMMV.
Cheers! Joe