If you are looking for a snake that obtains a decent size and is easy to care for id suggest a BCI. Most stay a managable size and are not extremely difficult to care for. My best advice would be to start browsing the forums on here and find a few species you like and research them throughly and then make a decision. The more knowledgable you can become on the species you want the less problems you can run into.
"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."