Here are my 2 tips for the top in each position
GK :
Ochoa
Akinfeev
DC L+R : so many to choose from
Domenico Criscito
Girgio Chiellini
Breno
Micah Richards
WB/FB L+R
Gareth Bale
Marcelo
Sergio Ramos
Rafinha
DMC :
Miguel Veloso
Ever Banega
MC :
Michael Johnson
Francesc Fabregas
AMC :
Lionel Messi
Jaun Carlos Carizo (he doesn't appear in the psv reserves till 2nd season)
AM L+R :
Matias Fernandez
Jaun Manuel Mata
Cristiano Ronaldo
Renato Augusto
FC :
Sergio Aguero
Bojan
These are only 2 tips i am providing i could have put 5 or 6 equally good players for each position. I have also tried to only put players available from the 1st season onwards however JUAN CARLOS CARIZO is imho probably one of THE BEST players in the game so in your 2 season SIGN HIM he will take a couple of seasons to mature but once he does OMG | 
