I saw a jungle carpet at the local pet store and all the employees said that it was puppy dog tame and never struck at anyone, I was amazed because I always heard about people giving them a bad reputation. I think it depends on the snake and how it was raised from a youngster. I find that the younger I get a snake the more I can train him to be easy going (the less baggage they have). The right environment really helps, a solid tub that makes them feel secure, the proper humidity and temps, and especially lots of food to keep them fat and happy.
I think that handling is good for any snake. I think you have to start with short sessions and really read the snake well and work up to longer sessions. I'm currently working with my SD retic who was a terror when I got him just a few weeks ago. This last session lasted about five minutes, I always keep him close to his tub so that if he wants to run he has a place to retreat. I started with sessions less than 30 seconds, now I'm at about five minutes and he is really chilling out, well for the most part. He still can be a bit nippy at first and pee on me LOL, but I think after a month or two we will move past that. Right now I'm handling 1-2 times per week, usually a couple days after a feeding when his rodent bump has gone away LOL.
I think if you got a snake right out of the egg and worked a lot with him you could tame any snake out there. I think reading the snake, feeding heavy when very young, and building trust is the key.
If you get a full size mature snake that's aggressive it will take a lot more work to tame them down and you may never really fully trust that snake. Especially if it's a large snake, the penalty for not reading it properly is a lot greater than with a small snake.
I'd say find a Jungle carpet that you know is tame.