If you're looking for a shell+liner combo in a glove (not a mitt), it may make sense to buy them together for proper fit.
My current glove system looks like this:
-very thin liner (nylon/spandex/somesuch). Great for manipulating little buttons and switches on my camera. Slightly warmer than wearing nothing.
-fleece gloves (slightly large, so I can wear the liner underneath if I choose). Primary glove for cold weather. Breathable, but only slightly water-resistant. Fine for incidental contact with snow. I don't let these get wet (unless it's raining). If I start to sweat, these come off.
-backup pair of fleece gloves (in case the main pair gets wet). Have only used these on rainy days.
-ice-climbing gloves. Nearly waterproof, good leather grips, warmer than the fleece. For situations where my hands are in frequent contact with snow or rock (or with ice axes), or I want a little more warmth. Snowboarders' gloves that happen to have good grips would be a good substitute for these (if you don't need padded knuckles).
-nylon overmitts. Additional wind resistance for extreme conditions, when grip is less important than covering that gap at the wrist.
The primary fleece and the ice gloves both stay on 'biners clipped to my waist, so they are easy to reach without stopping and they air-dry when I'm not wearing them. (The ice gloves have a handy loop on one finger so they hang in wrist-down position, so no snow gets in.)