I didn't bring up Trans Pecos rat snakes only because the request was for 'best python or boa'. My nickname is a pretty big hint (Bogertophis subocularis = Trans Pecos rat snake) & they fit perfectly as adults in a 40 gal tank. If you want any more info on TPs, just let me know, vivi? They are mellow & personable snakes, I've never known an ornery one & I've bred them in the past, but my first one came from a pet store, likely a w/c (adult) that was being mistreated, & it didn't take her long to mellow out even after all that. TPs don't go off feed in winter either...at least mine never do, they're easy to feed from tongs on f/t mice. (they tend to be 'polite' feeders, lol) I love their big 'bug eyes'.
I've not bought from VMS but have only heard good things about.