There are LOTS of great boas out there for beginners, and even more for someone with a bit of reptile experience under their belt already.

There really is no comparison between rosy boas and boa constrictors, especially from the perspective of snake aesthetics.

The first question I'd ask you is "when you say boa, what do you imagine?" If you truly want a "boa", then you probably already have an idea of what you're looking for.

The Boidae family is split into two subfamilies, which seperates "true boas" and "old world boas". Old world boas are generally smallish (3-4ft max), and typically burrowers like rosy, rubber, and kenyan sand boas.

When I hear "boa", I typically think of the "true boas", such as boa constrictors, tree boas, anacondas, rainbow boas etc.

Of all the true boas, Boa Constrictor Imperator is probably the most numerous in captivity in the US. It is a subspecies of Boa Constrictor, and many people keep it for a first snake. They are often called "red tailed boas" and "common boa constrictors". I prefer to use the term "red tailed boa" to specify Boa Constrictor Constrictor, the largest Boa Constrictor subspecies. BCIs are generally affordable, with numerous more expensive morphs out there.

I'd suggest you decide if you're more interested in old world or true boas. Once you decide which piques your interest more, it will narrow your options down to make it easier to find one of the species that do better in captivity.

If you come across a particular snake species that you just 'click' with, or particularly appeals to you, that's likely the species I'd suggest. So many people go with "option number 2" because they were scared off by terms like "intermediate". If you read up on proper care, very few snake species are out of the grasp of someone with a little reptile experience.