I like Rainbows, Dumerils, and Hogg Islands but I do have to chip in on the BRB part.
I have a pair of Brazillian Rainbows and have been arround/familliar with many other rainbow boas over the years.
While some of the smaller rainbow varieties may be as small in length as a ball python I have never seen an adult Brazillian Rainbow that was that small. My pair are 24 months old in 2 days and each is already reaching 5 ft in length.
Now my female is much thicker in girth then my male as he went off food during breeding season but he is now about the diameter of a standard broomstick while my female is about 1.5 times as wide(approaching double his mass).
Granted both my BRB's only have arround a foot or less of expected length growth they have a ton of girth still to put on before their full grown.
As far as temperment I cannot say for sure with non Brazillian Rainbows but BRB's will always calm down and stop biting if they are regularly handled from a relatively young age. The problems with biting occur when people aquire imported animals as subadult's or adults at which time the snake is already set in it's ways behaviorally speaking. Even wild caught babies will calm down with handling. Keep in mind though that the feeding and defensive instincts with babies is very strong so even with captive bred and handled babies there is an initial adjustment period where they bite alot. Luckily this is over with very quickly once they are being handled regularly.
After handling a friend of mines female Dumeril I have to say that they are both about equally handleable and friendly but that they have very different personalities. Dumerils seem more calm and cuddly while BRB's seem more headstrong and inquisitive. Although my experience with Dumerils is limited to only a couple animals.
In terms of care BRB's are a little more demanding but once you either get used to it or have a low maintenance setup explained to you they really have virtually no more upkeep then any other boa. The main thing is you restrict airflow to a minimum so that the humidity stays where it is. Other then that you can either use a hi moisture substrate or go with the low maintenance option of paper/other dry substrate in conjuction with a moss box hide and a water dish large enough for them to occassionally submerge in. In the low maintenance option all you really need to do regularly is clean the mossbox and change the water.
Overally I would say to get whatever interests you the most but to make sure you have a correctly set up enclosure and care information before you buy the snake. The requirements and sizes of these species(BRB, Dumeril, Hogg) are similar enough that none should be excluded from consideration just for that. And if you do happen to decide on a rainbow or just are curious about them at some point we are very friendly over in the rainbow forum also.
Hope I was helpful.
Sean.
PS: shameless oportunity to share a pic of my male from awhile ago(would post a Dumeril also but don't have one)
