what species do you recommend?

[thinkmore]

In my book of Reptiles and Amphibiens from Quebec and Maritimes its say 10 eastern garter snake maximum if you want more or other protected species you can ask for a licence .
But I think its 10 thamnophis whatever is the species Im not sure about san francisco garter .

But I'M 95/100 sure that its illegal to sell thamnophis all over Canada....

Wildlife is a provincial responsibility in Canada, so each province has its own regulations. It's illegal to sell WC animals, so that's why it's important to get an import permit so you have the paperwork to prove you're not selling wild thamnophis (if you decide to sell later).