There can't really be a true top 10 because there are so many different game set ups. Just because someone is great at BNW 1v1's on East vs West, doesn't mean they will be the same player in a large map game with 8 people on islands. Also, in multiplayer games there is so much difference in spawn and the human element that distort how talented people are. Then you have other factors of ....a person going random civs versus selecting civs.
I've never played anyone I thought I couldn't beat or that I thought was better than me, but that doesn't mean I haven't lost or would say I'm the best. Everyone loses, unless they play weak competition, are a liar, or quitter imo. I'm capable of sub T120 science victory, but that doesn't mean I can't spawn next to a great hun player and lose.
CivFanatics hall of fame is a decent gauge for science, culture, and diplomatic players, but even that isn't super accurate because going against an AI and real people is totally different.
Just my 2 cents.