We get this question a lot!
Here are the attributes we suggest for snowshoeing boots: Warm, dry and comfortable!
Warmth: Snowshoeing is an activity and you will warm up quickly. But, cold feet make for an unpleasant experience...so make sure you have a pair of boots that are properly insulated for the temperatures you will encounter.
Dry: Snow is frozen water...so when it melts you want to make sure your feet will stay dry! There are few things in life more uncomfortable than having wet and cold feet out on the trails. If your footwear doesn't have a waterproof feature, see if you can add waterproofing to the boots...particularly where there are sewn seams. Please note that not all materials can be easily waterproofed and that some waterproofing compounds can discolor your boots.
Comfort: There is a lot of foot-articulation going on when you snowshoe. So use boots that have a comfortable level of flex to them. This will prevent unnecessary rubbing and chaffing of your feet in critical 'rub' areas. Also consider the height of the boot. I find that I am more comfortable with a lower cut boot and gaiters, than with a high cut boot that has less flex and chafes my lower calf area.