I ride with gloves every time, summer or winter. It really stems from when I started taking jumping lessons when I was younger, I got the worst blisters on one of my fingers. Since then, it's sort of become habit to just wear them.
I reccomend leather gloves, because I've found that they hold up the best. Cotton works best for warmth, I think. Make sure they have reinforced fingers and such-they'll hold up so much longer! If you have a State Line Tack around you, they sell cotton riding gloves for six or seven dollars [here, at least].