Thanks, I read the p2 vs. p3 comparison. It's not quite the information I was looking for, because I'm not trying to decide on the version for a project of my own, but I'm going to teach a beginner. One consideration would be the version used in many of the introductory books and tutorials. A quick scan of Amazon shows that most introductory books use 3.
It might also become more clear what he needs when I find out what his larger plans are. He wants to use Python for something in his company, but I don't know yet what that is. Actually, I think his company uses mostly C#, and he chose Python as a first language (but eventually wants to learn C# too).