Spoiler:
1. Gervin:
.Gervin was probably comparable in terms of efficiency and repertoire, though he was smaller than Durant. He played a lot of minutes at guard (almost all of his minutes after 1978), so the difference between average guard and Gervin was still significant:
Gervin used slightly different techniques than Durant though, often changing release in mid-air. The use of the glass was also notable in his repertoire:
He also liked to shield his defender off this way:
[streamable]https://youtu.be/0iSsCy8jpwE[/streamable]
Gervin, despite being rather skinny, could be also physical. He liked using his size advantage over defenders, often pushing them with subtle hits. That said, he could be pushed around by bigger, physical defenders. Durant has the edge in terms of making separation, as he's bigger, longer and could carry the ball.
2. McAdoo
Bob was more like KD in a sense that he could hit his jumpshot no matter how good the defense was:
[streamable]https://youtu.be/siLRhzOndAI[/streamable]
He could also beat you off the dribble, so bigs struggled to contain him:
He also had similar post game, in a way that if you try smaller defender on him, he just shot over him:
[streamable]https://youtu.be/siLRhzOndAI[/streamable]
With that being said, I don't think he had as good jumpshot as KD overall. From my limited eye-test, he seems far more inconsistent and he had more games when his shot wasn't falling that Durant on average. I have also seen his jumpshot being blocked more times, because of slower release than Durant. That made him also relatively easier to defend, although when he got hot absolutely nothing could slow him down.
3. Kenon - this one is quick, Kenon wasn't even close to Durant in terms of midrange game. He was mostly an in-between player, shooting a lot of short jumpshots from the ~10 feet area. I just mentioned him because he was athletic freak with similar bodytype:
4. Bob Love is next, I will try to compile a video about him today or tomorrow.