#3 Yaya Toure (Ivory Coast)
Barcelona signed Toure in 2007 from Monaco, for a reported fee of €10 million. Even though he had his differences with Pep Guardiola, he was effective during his time in Spain. He started out as the holding midfielder in the middle and enjoyed a hugely successful time in terms of trophies.
He was part of the side which won the sextuple in 2009. Surprisingly Toure started at centre-back in the Champions League final against Manchester United, as Sergio Busquets filled his role.
Busquets continued to do that in the 2009/10 season, which meant that Toure was often placed on the bench.
The Ivory Coast international left Barca in 2010, moving to Manchester City for £24 million where he arguably achieved greater things.
He made 74 appearances in three seasons for the Catalan side, scoring 6 goals. Toure's stint at the Camp Nou was a brief one, but it was a successful one for both parties involved.