They will peform the same in snow, with the diesel using less fuel. Generally, the diesel is the better choice for contractors due to hours of use. But, if you don't expect high hours, the gas has the advantage that you dont' have to wait a long time for it to warm up, and they are much quieter. Warmup time on the diesel can be compensated for to some degree with a block heater.
The diesel will also probably run a snow blower better in really heavy, deep snow.
You'd probably also get close to the price difference back when you decide to sell in the future.