I've been meaning to write a series of blog posts about keeping warm while riding in the winter, and gloves were going to be my first topic. In my experience fingers and toes are the first to feel the bite of winter, and hence gloves and booties are first on my priority list.
As for the "perfect" glove -- I don't think it exists. I have an arsenal of gloves and I use them all. My wife thinks I've gone bonkers with gloves because I have so many, and because anytime we find ourselves in an outdoor shop, I'm checking out the new gloves. Here's a photo of the gloves I use most often. (I actually have more, but I use them for shoveling snow, skiing, etc.)
I generally use long finger gloves when it's 50 degrees (F) or colder. And I'll ride outside if it's 20 degrees or warmer. That's a pretty broad range and there's no way that a single set would cover it for my comfort needs. And because I leave in the early morning, and I generally ride in the mountains, the temperature changes change quite a bit as my altitude changes, and the sun rises. I also need significantly more warmth when descending than while climbing. In addition to the obvious reasons (I'm not working as hard, and I'm going faster, while descending) there's the fact that my fingers are wrapped around my metal brake levers while descending, which can suck the heat right out of your fingers.
I pretty much always choose two sets of gloves for every ride. Sometimes I only end up using one set, and the other set stays in my jersey pocket, but two sets of gloves gives me three options -- set A, set B, or both. And one of my favorite additions to my collection gives me even more options. Notice that the gloves in the upper right are battery heated gloves; they're no silver bullet, by any means, but when the temperature is below 30, I almost always have that set as one of my two. I like to have one set of tighter-fitting gloves, and one set of warmer gloves or mittens, so I can layer.
So until I get around to blogging on the subject, that's my two cents -- start a glove collection; layering is good; and battery heated is a nice option.
(NOTE: This poster owns a retail business selling weight conscious bike related products.)