easiest-corn, CB ball python
large snakes (bci-bcc) and extreme high humidity snakes brazillian rainbow etc...etc...
Advanced--"giant" breed snakes, rectics, anaconda's, burmese, etc.....etc....
Super advanced- hots
IMHO everyone is probably going to have it listed a diff way, that is just how I see it, you could also go by how agresive a breed is..
Neptune, Zion, Enigma,