Training is hard work! Good on you for doing that. Pits are sadly the most misunderstood but they are a great breed when done properly with consistency. People only need to meet one well behaved Pit that will change their mind about the breed.
If I were to get one, I would seek out a rescue. I'm not particular with the breed tbh. It's more for saving a dog or two. However, to answer your question, I'd go for the Alsatian/GSD or any of the mountain dogs that can stand the cold. I live in the mountains and we have brutal winters. We have Swiss mountain or shepherd dogs that are perfect for the role as well.
Alsatian and GSD are the same. I grew up calling them Alsatian when I learned english. It's probably outdated. π