This is one of those topics than can be debated forever. Mainly, whatever seems to work for you is what works. A lot depends on the type of snowshoeing you do. If just clunking around the woods out back of your Maine country cabin, then as long as you don't get frostbite any old shoes will do. But certainly footwear makes a difference. The right match between boot and snowshoe will keep your feet warmer, improve your snowshoe control, and improve efficiency by giving you more leverage over the snowshoes. The tradeoff is that you usually end up with heavier boots, so you're paying a penalty for dragging around those extra ounces. A good compromise is the current generation of snow boots, which are essentially light hiking boots with some extra insulation. Columbia's Bugabootoo ($115) is an example of this type of boot -- it's designed specifically for light winter hiking or use with snowshoes.
Myself, I tend to prefer heavier footwear. I like to wear light plastic boots when snowshoeing, such as Koflach's Degre ($250). My own boots are Asolo Guides, which now are called the AFS Guides, and have uncertain availability in the U.S. Still, that's probably more boot than you want to fiddle with.
In general, though, I think you're best off with a good-quality rough-terrain hiking boot with all-leather construction. Whether the boot is insulated is of no matter to me, good wool socks (SmartWool Mountaineer ($20), over-gaiters (REI Mountain Gaiter, $40) and even insulated insole inserts (Insolator insoles, $10) all can ensure that your feet stay warm. I would advise against low tops -- you'll have soaked, cold feet in a matter of minutes, unless the snow is so hard that snowshoes themselves are somewhat superfluous.