I've always had a problem w/ Nike shoes - whatever the sport. Too narrow in front, too wide at the back. They feel like a man's shoe.
I've had good luck w/ Sidi & varying success w/ Shimano. Actually, w/ both, I have to try on a lot of their line. Some of my friends love some Italian brand (& I'm at a loss for the name) but they're very pricy.
In the interest of full disclosure, I still don't have a mountain bike but use mt bike shoes for touring.
Debra