Can't decide on which boa to get.

[BFE Pets]

I currently have a ball python, and I love it, but I want something a little more sociable. I am thinking about getting some type of boa. (it will probably be 6 months to a year before i get it, because i need to do research) I have thought of a few I might like, but I can't decide. So, I want to ask you. Which one would be good for me? Here's a little bit about what I am looking for:

-I want something docile and something that won't get too big (6 feet max), but will be bigger than my ball.
-I want something that likes to be handled more than my ball python.
-I like the big heads of the boas. There's just something about it that intrigues me.
-I will keep it in a tub of whatever size the boa needs.
-I am good with keeping the humidity of my ball python, and she has a constant hot spot, but her ambient temps usually stay about 75-85, depending on if the heater is on her. So I need something that can bare a bit of temperature gradient. Or something that doesn't require high temps. That would be even better. If not, I can accommodate to its needs.
-I will probably get a male.
-Not very interested in getting a morph.
-Relatively low prices would be nice.

I have thought about a Dumerils Boa, a Leopard Boa, a Brazilian Rainbow Boa, and a Hog Island Boa.

IMO A carpet python does NOT fit into what you are looking for!
1 something docile Carpets are not known for being very docile. they do calm down with regular handling but for the most part umm still gotta watch them and adult female coastal carpets can reach lengths of 9-12 feet for some localities.

2 something that likes to be handled more than your ball. well they tolerate it but they are very active. i'd say they handle more like a retic lol jmo

3 the separate neck and head. yes that they do have

4 something to keep in a tub. they are semi arboreal the minimum suggested enclosure for an adult carpet is 3' x 2' x 2' with a 4x2x2 being preferred by most keepers.

I'm no expert on carpets by any means but I own 1.2 and have done a little bit of home work on them before getting them. my jungle male was a total psycho when I got him. after his week of "me time" I tried to handle him long enough to snap a couple pics and he wasn't having it! I got nailed 14 times in under 2 minutes! that is no exaggeration either. That was around valentines day I can now count on only getting hit when I reach in to get him but it was a lot of work to calm him down to that. My diamond carpet cross is a total sweetie and hasn't even thought about taking a swing at me (also a baby) my 6-7 female coastal is cage aggressive as all hell and is well on her way to being hook trained but you don't dare reach in to drag her out unless you feel like getting stitches! once shes out shes completely cool but DO NOT reach in her house! My vote is always and forever a Dumerils Boa! total sweet hearts and fits very well into your requirements.