Expanding my collection?

I'm looking at getting another snake and boy oh boy, is the itch serious. There is a few that I have been interested in, of course all boas. I understand I have just gotten my Ball Python around February but I have helped handle my grandfather's old 6ft Colombian Boa Constrictor, Ralph, on many occasions. I also will research loads more into it once I finally pick (How could I? So many great choices). But this will still be my first own personal boa. I know I could go on websites and see the "personality/trait" list but I figured it would be better to get all of your guy's experience with these certain Boas. Also any tips would be awesome :)
In no particular order:

1. Brazilian Rainbow Boa
2. Red-Tailed Boa
3. Caulker Cay Boa Constrictor
4. Colombian Boa Constrictor
5. Dominican Red Mountain Boa

Columbians...so many morphs but not overwhelmingly like BPs


The BronX BoA

Rainbows have higher humidity requirements, so that's something to take into consideration. Columbian red tails are great. I have 2 and they are absolute sweethearts. You still have humidity requirements, but they aren't as demanding. Caulker cays are going to be pretty similar, only in a slightly smaller package. And Dominican red mountain boas are absolutely adorable! Not so easy to find, unless you have them shipped. I don't know their husbandry requirements off hand, but I do know the babies are better started on small feeder lizards. I'd say that a central American boa would be the best to start with, but I would thoroughly enjoy drooling over a progression thread of a DRMB :)

What did you end up going with? I'm seriously looking at Caulker Cays right now.