Young Boa Housing Question

[Alexandra V]

I'd go for the 36 x 20 x 13.5 (unless it's a very young boa), because it will more than likely outgrow the smaller one quicker, and boas tend to handle extra space a lot better than a ball python and not stress out. My boa has a cage only slightly smaller than yours ( 24 x 24x 12) and she's about 2 feet long, doing just fine, no stress or nothing.