Haven't played with enough teams/different players to name 5 concrete must busy for any side but what i will say is Javier Pastore is a must get for any team who can afford him, i respectfully disagree with ananasfan above who says Paulo Henrique is the best playmaker in the game because from my experience no one comes close to Pastore in that regard, the kids an utter genius and his stats go through the roof after a few months of decent training.
Just coming to the end of my first season with City and Pastore has 16 goals and 27 assists with an average rating of 7.60 over 50 matches.
Other players whove impressed me are Ryan Shawcross and Eden Hazard.