Most riders have glove problems in wet weather. Leather becomes soaked and then stays wet for a long time after the rain ends. Gloves with waterproof interlinings can feel 'slipperier' and seem less comfortable. This type also doesn't solve the problem of saturated leather remaining wet for a long time. Waterproof interlinings are also relatively fragile. They can tear in the course of ordinary wear, usually long before the rest of the glove has worn out.
Rubber over-glove rain covers keep leather gloves dry but interfere with good control feel. During long rain periods, leather gloves underneath eventually become damp because these rain covers are not breathable enough to vent all of the moisture hands can produce. Neoprene type gloves are uncomfortable to wear for extended periods. They cause muscle fatigue because of their springy pre-formed shapes, and they do not provide precise control feel because of their spongy-ness. Also, they don't breathe or provide much abrasion resistance in a crash.
I use different approaches for different wet weather circumstances. For most riding I like our Elkskin Ropers with a touch of Heavy Duty Scotchgard sprayed across the back of the knuckles, fingers and backsides of the glove. In many situations the waterproofing spray provides just enough wetting resistance. Even if not, I sometimes decide to continue riding anyway, allowing the gloves to gradually become wet, knowing they will have time to dry later. If it looks like a long day of wet riding is ahead and I want to stay as dry as possible for as long as possible (or if the temperature is slightly cooler), I put on Aerostich Triple Digit Rain Covers before starting out. On days when it looks like it may rain intermittently, I will carry the left raincover in a left side Darien pocket and the right one in the other side. On a smooth, straight road without much traffic, when I'm not going too fast, I sometimes put on the rain covers over my regular gloves as I ride. After seeing bad sky conditions ahead, it takes about a mile to get them on. Do not try this. It is easy to wobble off the road and crash. Normally my rain gloves live in the tank bag and I pull over to put them on.
For commuting on wet days I like synthetic motocross gloves because they dry so quickly. Unfortunately, these types of gloves have limited abrasion resistance and are not suitable for protection at higher speeds. One model I like is the Cold Pro, but there are many others.