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I'd be much more inclined to go with a hognose for you based on your experience with cornsnakes. Out of curiosity how old are you? I'm sure I'll get chewed up for attaching a random number to it but I wouldn't want someone too young owning a boa. I'd want to say around 15 is probably a good age for something like that because hogs aren't too big, just rather girthy.
If you are looking for something drastically different and you want a bigger animal maybe a hog island boa would be a good fit.