Sri Lanka with the entry of Mendis will be boosted further. Personally, I feel they have the best bowling attack of the subcontinent (Vaas, Malinga, Murali, Mendis and others).
Pakistan - well dont know how they will fare against the big teams. I have not been that impressed with Shoaib Malik after the initial promise. Pakistan really need an aggressive and imposing captain who commands the side on the field.
India - After the exit of Ganguly/Dravid and the entry of the youngsters under Dhoni, India have transformed themselves quite well. Dhoni's captaincy is helping the team, and with the youngsters performing well in Australia, they are the hot favorites. Once Yuvraj starts firing, they will be unstoppable. They have a little weak bowling attack (Ishant has boosted it a bit but still our bowling in ODI's is very weak).