I like the conti type tires better. I am currently using Swiss Army inverted tread tires, similar to the Nashbar Elevator. I've used "slick" treads before on the same bike. The Geaux and similar tires with cutout delta shaped sipes or patterns seem to do ok.
I had some Tioga City Slickers gumwall 26x1.5 road tires which had a recessed portion all the way around the center of the tread. The rest was slick with little arrow shaped notches for water clearance. They were great for wet traction but still slung water up the back on this bike, because the frame didn't block it, and the motorized bicycle goes faster!
I have made my own motorized bicycle rear fenders before out of corrugated plastic (see my page happycheapskate on motoredbikes.com for pics).
If all you ever ride is road and never ride through any mud or gravelly areas, go with the slicks.
But the heavy duty Continental inverted treads will get you out of mud and deep puddles, hardpack dirt trails, and snow a lot better.
From experience on road bicycles, I would say that narrow file tread tires are best for snow! But you need something besides rim brakes or you will be in a world of hurt.
Rally car racers use very narrow tires for snow racing. Some 4x4 mud vehicles use tall narrow tractor type tires instead of giant mud boggers and do very well.