In wintertime when air is around zero and water +5C I use Xcell 5mm gloves.
They are thick and they hinder a bit with paddling, but its less worse as without. they seem to last as well...4y old :)When its getting warmer/less cold

, I use 2mm gloves till its doable without them.
If you don,t have allready an hooded suit, also invest in a decent hood with flaps inside AND over the neck collar to seal it up tightly.