I always get the $10 slippers from costco or whoever has a sale.  I picked up a pair of these and wow, I'm never going back.  They're wool, warm, don't get sweaty, and they're extremely comfortable.  As many know, wool is a great fabric that stays warm even when its wet, but isn't excessively hot.  The downsides for this are the little rubber dots and wool bottoms won't take much concrete or any outside action if its wet out.  They also tend to stretch and become a little loose, but I've put them in the front loader on gentle and they washed up a little tighter, almost like new.

When I wear these out, I'll buy another.  A real improvement over the $10 slippers.