Both Extremities and Sealskinz would make an ideal purchase.
Their gloves are high quality, and some of them are quite effective at keeping your hands dry.
Now looks the best time to invest in a pair of new waterproof gloves, as i managed to pick up a pair of Extremities for well under retail price, and they are very warm, actually too warm for summer use, more an autumn winter glove, and so far very waterproof.
As for the right glove, that can only be done through trying them on in a good shop.
Its a difficult choice, Extremities or Sealskinz, both make high quality gear, so i suppose its all about the price.
If you can grab your self a Christmas or new year sale bargain, then both companies will do the job nicely.