Best pythons or boas??

[Cheesenugget]

If you can find them, rubber boas would be great in a 40g. Added bonus with them is that they do not require supplemental heating and thrive a room conditions. They are difficult to track down however

Another option I did not see (granted, I did power skim so I might have missed it) would be sand boas

VMSHerp breeds rosy boas, which is more common than the rubber boa and falls within the same family. I had a sand boa from him and she was great. My corns came from him too. He also breeds transpecos, these are not commonly found but I heard nothing but great stuff (Boger knows more). But a 40gallon may be too small for a transpecos?

His website is easy to use, if the snake did not transition to f/t (he tries to do that for all his hatchlings), he will list what it is eating so you are not caught unaware, and any questions or changes to the order can be made via email and he responds very quickly.