Kepa has for me a better structure than Pickford. The english GK is 185 x 77kg and the young spaniard GK is 188 cm x 84 kg.
I could name other interesting young GKs like Onana or Lafont, but recently how many promising young GKs have failed?
Areola returned to PSG, was ready to be a starter but Emery replaced him with Trapp. Klopp signed Karius, promoted him as starter and but replaced him with Mignolet. Sevilla have Rico (U23) but isn't good enough for them, imagine for us.
Maybe with Ederson at City, Gerónimo Rulli (he was under contract with a third part company linked with Manchester City) could become available, but is he good enough?
Donnarumma is very young, his contract will expire at the end of next season, but his agent is Mino Raiola and for his client will ask a monstre wage. Apart that, he is good, but probably a little bit overrated.
Other good names are Pickford (like Jakey said), Butland (injury-prone?), Bernd Leno (Karius 2.0?).