Look for strong handles. I've had two slow cookers, one a GE, and the other a Crock Pot, that have had the handles break from the appliance while I was carrying something hot. It wasn't pretty either time.
I now have a Hamilton Beach Stay or Go model that has worked very well for me. It's nothing fancy, but has very strong handles, and built in clips for securing the lid to the slow cooker. That makes it much easier to carry foods to places without worring about spills while traveling.
Seeeeeeya; Goodweed of the North