Avid BB7 up front, rim brakes on the back because my cheap Hybrid had disc tabs only in the front.

There's no comparison for riding in the winter; I've had the rim brakes simply do nothing when I squeezed them due to freezing rain on the rims. And even with Koolstop pads, different conditions result in slightly different braking power. With discs I know what I'll get when I squeeze the brake.

BTW I've been running cheap knockoff pads that I got for $6/set from eBay. They last a little longer than the Avid pads it came with, and the braking is the same. Avid pads are around $18 I think, I've never actually bought any after pricing them.