For a first time I'd go with a BP, easiest snake I know of that will have girth when an adult, you don't need a big 75gal tank they tend to like to stay in small places where they feel secure a 40gal breeder should work for its entire life unless you over feed it. Mine has never bit and never skipped a F/T meal but from what I hear I may just be lucky. I would avoid a Boa since they seem to need a temp. maintained within a few degrees to stay healthy and humidity can be tough to keep up at the levels they need unless you live in a naturally humid place (unlike me). If you go with a BP I'd go with a morph if you can spend the money on it, you should be able to find something pretty to look at for $500 or less (check out bumble bees if you like yellow/black). You could find a nice looking Boa for a lot less but I would avoid for the reason I already gave. a CP as people have said are a bit more aggressive and unless you are already comfortable with handling snakes (which I assume you are not since this will be your first) I'd take a BP and if you find yourself comfortable and in love with the idea of owning a snake get a CP later and expand your collection. Be in mind you're in for a pet that can live up to 30+ years so you better like what you pick out, I hate reading about pets that need to be saved because their owners neglect them.