I just have a dumeril's boa, but you could always get a boa constrictor imperator male if you're worried about size.

If being docile and handleable is highest priority though, I'd try dumerils again. Their ease of feeding seems pretty split, they're either pigs that eat everything or are picky with f/t. Looking for an older dum (over a year old) will give you a better chance of no feeding issues, and buying from a reliable breeder or keeper.

You see posts about boa constrictor bites, but almost never see one about dums, even within dumerils communities.