This is our favorite NNN-compatible cross-country boot, no contest. The BCX 6 has exceptional side-to-side stability for its class, thanks to a plastic exoskeleton and cinchable power strap around the ankle, combined with a stiff heel cup. The midsole flexes enough to let you push off powerfully, but not so much that the boot bends and crushes your toes. It can easily turn the biggest, waxless Nordic skis like the Snowbounds (or even the Guides).
Inside, a Thinsulate-insulated bootie laces to just above the ankle, then zips inside a high-cut neoprene cover for warmth and weather protection. Plush memory foam throughout the ankle and heel conforms perfectly to your foot, eliminating pressure points, and the tongue is plastic-reinforced to protect your shin from lace pressure. Clincher: It's warmer than any other cross-country boot we've tried. Best for wide feet. $199; 4 lbs. 3 oz. (43); unisex 36-49; fischerskis.com