Medium-size Bagmaster bag if pistols only; has outer pockets for 2 and plenty of room for ammo, belt and other accessories, provided you leave the kitchen sink at home. Have had it for 15+years and it has held up GREAT.
For 3-gun, I often use the same VooDoo double-rifle case Ken mentioned and if I'm not mistaken, Jesse T has one also. Big, heavy zippers, plenty of pockets and padded straps to carry as a "backpack". Can get heavy so sometimes I opt for simple single long gun bags and a VooDoo backpack for ammo and 3-gun accessories. Depends on the match and my mood.