As someone who has been hit by a Canebrake rattler and knowing a few folks who have been hit by Copperheads, I can tell you for certain that Copperheads are definitely my preference for being bitten
) Still, you need to understand that Copperhead bites aren't anything to laugh at. You can still wind up missing a finger from gangrene, or have reduced mobility in a finger joint, and you won't be running any marathons for a few days after a CH bite. In other words ... take them seriously as a venomous animal.
However, as a first hot snake, I think a CopperHead is the obvious choice. It has been my experience that even wild-caught specimens will calm down considerably and I've NEVER known one to have the kind of temper you see in Eastern Cottonmouths. Also, they can be a strikingly attractice snake, as well. I know guy locally who owns five or six of them and he has a couple that are downright gorgeous little things. Beautiful creamy white ground colors with pinkish hue and strong bronze bands.
For a first hot snake, go with a Copperhead. They are easier to care for than pygmy rattlers, much prettier than most pygmy rattlers IMHO, and won't completely light you up if you get careless and get popped.
Minh