Sealskinz used to be amazing but they outsourced production and they are now somewhat expensive and quite average. I have a pair and am not particularly impressed with them.
A lot would depend what you do - if you're just walking and don't use hiking poles then nothing beats mittens. If you want to pick up some dachsteins and a set of waterproof overmittens it'll probably cost you around 50 quid and you'll have warm and dry hands in the majority of conditions you're in.
Anything else comes down to how much dexterity you will need, if you're holding tools, if you'll need to move snow barehanded etc. You don't often have to spend a fortune on gloves to get warm ones, but I've found that warm climbing gloves which have some kind of abrasion resistance are usually not cheap.
Also, it goes without saying but have a spare pair in your pack (even if they're cheap, light gloves). Nothing ruins your day than a winter trip where you lose/soak your gloves and you're left with painful hands.