Nikwax. Yes yes yes.
I have ridden through storms that would drown a frog and I have yet to have my gloves let me down.
I'm sure it helps to start with a great pair of gloves though, so take that for what it's worth.
The two pairs I rotate through are 1) BMW Atlantic gore-tex gloves, and 2) Gerbing T5 heated gloves.
I'm yet to have wet hands, ever, in over 200,000 miles with the combination or either of these gloves.
Reviews are good. Getting the right reviews are better.