You must remember, no matter how calm and tame your snake is, it is still led by instinct! I know that has been said a thousand times, but if your going to get a large snake, that has large teeth, you must take into account, that you may be bitten one day, and if you are bitten, will you EVER try to hold it again, and if not, will you still take good care of it?
That being said, My baby green is awesome, I didnt get to pick it out of a bunch, my former pet store ordered just one, for me, and I love him to death. He is even calm when eating, just barely strikes the mouse. I also have some knowledge with the big snakes, and I have been "Hit" by them before, and while it doesnt hurt so much, it is VERY SCARY! From what I noticed about all reptiles, the more you put in, the more you get out, that being said, if you decide to get a Anaconda, you have to play with it, I would say at least 3-5 times aweek, and more if you can. I have handled my Columbian RT so much, that if she doesnt want to be held, she shoots her head back down into the cage and grabs on to something, and if I keep messing with her, she starts to hiss, very loudly, and that tells me "Leave her alone", but she have never struck at me, even when I am in perfect range and she is hissing her head off, she doesnt want ot bite me, she just wants to be left alone. My green, though, seems to want to come out on a hourly basis, so I am in the process of building a exercise tree for both of them.