This has led me to the thought that I've been thinking about this question all wrong, and that instead of thinking of the authors of the early years who are mostly forgotten thanks to the years but are kept alive by people who like knowing about these things, what of the authors who did very different things at the time when the influence of Tolkien was at its biggest?
A lot of those names have been covered, but a quick look through says neither M John Harrison or Tanith Lee have been mentioned so far. I think Samuel R Delany hasn't been mentioned either, nor John Jakes. I'm sure there's a bunch of other authors from that period unnamed too - and not just because people haven't been thinking of it, for I see John Crowley and Avram Davidson and Roger Zelazny and so on.
No John M. Ford either now I look closer.