I second this, if your core is warm enough, your body will send warm blood to the fingers and toes. However, if your core is cold, your body will conserve heat for the vital organs. Better still, if your core gets hot, your body will send the blood to the extremity to cool, which will in turn keep fingers warm. I like to ride warm enough to get a sweat going and open the vent to manage the moisture.

That said, here are my gloves for the cold rides in MN winters:

I use Pearl Izumi gloves for the 20F to 0F range - Men's ELITE Softshell Glove - Pearl Izumi

For temps below 0F (tested to -20F) - REI Switchback Gloves

It should be said (or repeated), everybody's temp range and cold comfort is different. My warm gloves at 0F might not be warm enough for another rider at 30F. Example, riding home last night (around 20F), I met another rider. The other rider was fully covered with snowboard helmet, balaclava, goggles, etc; me: summer bike helmet with wool skull cap, my face was bare, glasses put away because they fogged over, jacket half unzipped. Bottom line, find what works for you - everybody's different.