Dubravka is not just better than Darlow, he's one of the best goalkeepers in the Premier League. Even in the aerial game, which is his worst ability, he is superior to Darlow. And beware, Darlow has been at a tremendously high level this season, But in another team, without having to make saving stops almost every 15 minutes, Dubravka would be at the level of the best and would get a lot of clean sheets. What Goalkeepers are better than him in the PL? Alisson (and he is in a terrify season). No more.
Ederson is so much important in ManCity because his feet ability, no more. Is a normal GK.
De Gea was very good player. One of the best in the world, but the 2018 World Cup changed some in his mind...
Pickford? Mendy? Kepa? Nah.
Dubravka is in the same level than Leno, Rui Patricio or Lloris just after Alisson.