Cinebench points per Watt according to a recent c't CPU comparison [1]:

  Apple M1: 23.3
  Apple M4: 28.8
  Ryzen 9 7950X3D (from 2023, best x86): 10.6

All other x86 were less efficient.

The Apple CPUs also beat most of the respective same-year x86 CPUs in Cinebench single-thread performance.

[1] https://www.heise.de/tests/Ueber-50-Desktop-CPUs-im-Performa... (paywalled, an older version is at https://www.heise.de/select/ct/2023/14/2307513222218136903#&...)