I currently keep or have kept every species suggested so far, and frankly I disagree.
Kenyans - generally docile, but a few are really snappy and don't grow out of it! Males can be difficult feeders, as mentioned above. And if you keep them under proper conditions, you rarely see them.
Western Hognosed Snakes - take a read down the Hognose forum and look at all the posts about "my hog won't eat" or "my hog hasn't eaten in 3 months". Doesn't happen to everyone, but it does happen sometimes.
Ball Pythons - not a good beginner snake for more reasons than I could go into here (and I currently have a pair and have kept them since the late 70s). And again, under proper conditions, expect to never see your BP.
I suggest two things -
If you want a pet to sit in your lap, get a cat. Snakes don't enjoy your company and probably have limited awareness of you as a living organisms anyway.
If you insist that this is what you want in a snake, get a Rosy Boa. Dog tame, easy to keep, fat and lazy snakes.
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Chris Harrison