Asolo makes a superior line of boots; plastic and leather. But one boot stands alone at the top of all mountaineering boots: The AFS Expedition plastic mountaineering boot.
The Expedition comes in a bright yellow outer shell with an orange removable liner. The liner is a slip-on type and has a sole embedded with tiny copper wires to conduct heat. The shell features brass pulleys to lace up the boot that really help cinch it tight. The boot is exceptionally warm (too warm for anything above 0 degrees F.) and water proof. Being step-in crampon compatible, the boot was very stable when we tested it out on vertical ice.

Asolo makes serious hiking boots as well as light hikers, trail shoes and trail sandals.  Asolo's mission is to realize a boot that responds to your needs: from walking to trekking, from backpacking to the most difficult ascents on ice or mixed terrains, in all conditions and on different altitudes.