If you want a mitt that offers retro roadie chic and traditional back-of-the-hand tan lines, it's got to be Rapha.
They do two: this Criterium glove and, if that's not exclusive enough for you, the Grand Tour for a cool £80! The Criterium is made from kid leather apart from the thumb upper, which is towelling. Leather is water resistant, breathable, abrasion resistant and long lasting. The thumb arch is reinforced with more leather and the palm is padded with '2mm pads from army sniper gloves' (should you wish to shoot anyone).
Bike comfort is generally good, although I'd like a bit more over the ulnar area; my hands ached here. I'd wear these for racing but not for clocking up the miles. They're close fitting, grippy, and the fact that they're twice as expensive as the others is immaterial if, as is likely, they last twice as long. They're fastened with a Velcro strap with an understated Rapha logo.