This is an interesting topic, because I am also looking for a new set of knee bands.
I am going with the rehbands, because of the great reviews they get. However, they are very pricey.
Right now I have a pair of Tommy Kono Knee Bands, I am with them. They give great support and warmth, however they did tear after only a few months.
If you are looking for a cheaper alternative, you can check out vulcan support gear
TheWeakGetEaten - VULKAN Supports for Athletes, Strongman, Highland Games, Weight Lifting, Power Lifting, Body Building.
I am getting the elbow sleeves, and warm pants from Vulkan for Christmas, so I can give some reviews after then