someone told me act 2 snake runs was like 1.8 b exp for the same duration. not sure how accurate that is, but i think generally speaking,

1. if you are not so well geared
2. a noobie
3. can't get a good group who knows what they are doing to do cota properly,

then your better off doing snakes in act 2 for the quest called a royal audience......

It only makes sense to do cota if you can do it efficiently with a will experienced and geared crew. Also the downside is it's much tiring than snakes, because of the elite factor you need to avoid .... (arcanes, poison, blizzard etc etc...)