scott i second the finish line cross country recommendation. i've been using it for several years and it is awesome! i can literally go months of riding in the rain without re-lubing. i do wipe my chain down after every wet ride which seems to help a lot.
i tried the ATB and it sucked, made my chain make all kinds of weird noises and wore off pretty quickly.
FWIW, i'm still on the first small bottle of finish line cross country that i bought about 3 years ago. plenty left in it...