Choosing Guinea over Spain has an explanation. Ilaix Moriba is considering what is best for his future, which points to the Premier League with Chelsea or City. And to play in the English League, he needs to meet certain requirements, which he would achieve by playing more games as a international.
Ilaix Moriba's desire to play for Guinea instead of Spain has more than one explanation. Beyond the fact that the Barcelona player was born in Conakri, the capital of Guinea, there is another reason for this choice.
Playing for the national team gives footballers points to be able to play in the Premier League, where the young Azulgrana has several suitors, such as Chelsea and Manchester City.
The English League, as 'Mundo Deportivo' reports, demands certain requirements from foreign players based on a points system, and being a full international adds up to a lot. Footballers who want to play in England must present a certificate called Governing Body Endorsement (GBE), something like a work permit that is based on points.
You need 15 points to be able to play in the Premiership. The 'EFE' agency details the criteria for these points: having played matches for the national team and the national youth team; the quality of the player's former team, based on the league they are in, their position in the league and their progress in continental competitions; and, as a third criterion, the matches played for the club.