The new deathadder 2013 is not the best mouse ever, BUT it has the best shape I have tried yet and the sensor is VERY good. I also like the grip on the 2013 edition, but I cant compare it to other versions.
But since for me the shape and sensor are the most important features of a mouse, even if it's not necessarily the most well built mouse ever and the scroll wheel is ok but could be improved, it is still my favorite mouse yet because it's super comfortable to use and very precise.
So in the end, even if it's not the best mouse ever made, it's still the best mouse I ever tried because it's the one I most enjoy using. The hard thing with mouses is that it's hard to know if you will like it or not without trying it. So if you hesitate between these 2 mice, try the one that interest you most and then you will see if you made the right choice!