I've said it since he was with us that to say Reece James was our best ever player was ridiculous when we were in the championship & he was playing against Championship players
However there was no doubt that he would be more than up to the top flight when he returned to Chelsea. He may also turn out to be one of the best players that the world has ever seen but (IMO) to say he was our best ever player whilst with us is a bit of an insult to all those who played for us during our 8 years in the top flight coming up against your Gerrard's, Ronaldo's & co
Personally I wouldn't even consider him for our best ever player - had he been in that 05/06 Jewell team or the Bruce one that was challenging for Europe or any of the others from 2005 to 2013 then maybe, but not whilst he was with us & at the time he was with us
For me players who were consistently good whilst with us in the top flight would be the likes of Leighton Baines, Jason Roberts, Palacios