Gordon Banks was very highly rated when he was playing, but it seesm that his stock has increased even further as time has passed. I think that's mainly to do with justified reappraisal, but I wonder how much of it is to do with, 1) being the only English keeper to win a WC medal, and 2) That save from Pele in 1970. I'm not being critical at all, I'm a big fan of Banks.
In my opinion, the best three keepers ever are Pat Jennings, Rinat Dasaev and Lev Yashin.
Jennings is one who time hasn't been as kind too, and a lot of "experts" seem to have forgotten just how good he was. Dasaev was so solid, very good on crosses and so commanding, and Yashin actually took goalkeeping to new standards, being the model for all keepers of his era to aspire to. Others I'd mention would be Banks, Preudhomme, Meier, Buffon, Shilton and Schmeichel.
Nix, Leyton Orient and Alloa Athletic supporting schmuck.