Sounds like you're looking at garden tractors, and there's not a whole lot of modern garden tractor talk on this forum. You might do well to talk with a few local dealers, who can probably tell you which brands do better or worse for snow duty in your local conditions, if that's what you're considering.
One thing you will want to consider is that nearly all garden tractors are limited by weight, never by torque or horsepower. You will nearly always lose traction, before you stall the engine. So, wheel weights, ballast weights, and tire chains are your best weapons, when trying to plow snow with a garden tractor.
A snowblower is often a better mate to a garden tractor, due to the weight / traction issue, but will limit your choice more on brands and models. I am not sure if they are as common today, as they were many years ago.
But before calling it done, what sort of area are you trying to clear? How much time do you have for the job, and how frequently? What brought you to the conclusion that a 20 hp tractor is the solution?
Posting your location would help.