I would have said David Niven. Felton conspicuously limited himself to the “official” films, thereby implying he was aware of Niven’s status.
Niven appeared as James Bond in Casino Royale (1967), and is, with the exception of Sean Connery in Never Say Never Again, the only other man to ever portray Bond in a non-Eon Productions film. Niven had been Bond creator Ian Fleming’s first choice to play Bond in Dr. No. Casino Royale co-producer Charles K. Feldman said later that Fleming had written the book with Niven in mind, and therefore had sent a copy to Niven. Niven was the only actor who played James Bond mentioned by name in the text of a Fleming novel. In chapter 14 of You Only Live Twice, the pearl diver Kissy Suzuki refers to Niven as “the only man she liked in Hollywood”, and the only person who “treated her honourably” there.
Timothy Dalton. He was, in my mind, the only ones who played Bond as Fleming wrote him. Lazenby didn’t do it for me.