This is discussed extensively on a couple of other forum sites, including ADVRider, the Motorcycle Tourers Forum, and the Ironbutt site. General consensus is that the very best gear is Warm'n'Safe, although several other brands get decent reviews. For the price, the heated gear at CycleGear is actually pretty good, and Moto Guzzi cheap.
Check
http://www.warmnsafe.com/heated-gloves/ - and don't forget, the key to keeping warm is to keep the core warm, so a jacket combined with the gloves might be a very good idea.
I have psoriatic arthritis / ankylosing spndylitis and Raynaud's on top of it, and I can still ride down to icing temps when using proper gear.