I think Hogg Island boas can exceed 4-6' (though males might stay smaller), & personally I'd go with a Peruvian long-tail or Dumeril's...but this is a really personal
choice, sometimes you just "go with your gut" when you see what's available too. Just research the care on each to make sure nothing will turn you off, as all
are a little different. I like plain ol' male BCI's too, but that's not on your list.