I play as Spurs, 3rd Season now and narrowed it down to the same choice after Ben Davies was sold. I went with Gaya fee rising up to £26M purely because i had Grimaldo on last years FM and had not signed Gaya before. They are both very similar and both a good option. After I had agreed the transfer for Gaya, Grimaldo got unhappy and Man City signed him for just £13m..so may be worth tapping them both up.