Valve on water heater

I'm going to be replacing the inlet valve on my water heater along with the heater. The valve thats there is corroded to the point where I can't shut it off. It looks like a big gate valve. Is there any specific kind of valve to use or one that's less susceptible to corrosion? Thanks
Neil

I also recently replaced my water heater and the cold supply shut-off valve. I went with a 1/4-turn brass ball valve (3/4" copper line).
The corrosion problem should be reduced with dielectric nipples in the hot and cold sides of the water heater itself. Make sure that you have them and not plain galvanized nipples.
Good Luck!
Mike

Every water heater I've seen has some with factory installed nipples that you just attach a female adapter to. I suppose if you get one that doesn't have them be sure to get the special nipples. Like was already said use a good ball valve. When you solder wipe the joint, or if not clean it well when it's dry. The extra flux over ten years isn't good for the pipe either.