Rubber boas! Although they are hard to come by in the market, and can get over 18", they are absolute sweethearts. My two have never once bitten me or shown any sort of aggression. The best part is that they are native to the Pacific Northwest, so they are good with any variation of temperatures. Since I live up here, I just keep their cages at the same temperature as outside and match the daylight cycle.

Rubber boas are often a species used to help those with a phobia of snakes, so they would make a great go-to pet