I agree Corn or king, but a royal python as a first with no experience may just be to much for him, if he gets one that has the notorious intermitnt feeding responce then he will be pulling his hair out. (Just a thought) its always better to have some experience before you go down that road, but thats not saying they are all like that.
A grey ratsnake would be a good one, great feeders, usualy nice and calm and can grow to a nice size.
or maybe a bull snake, another good one to start with that grows to a good size.
paul.