Like DOOM, the Quake franchise was highly influential for the FPS genre. While some may argue that Quake or Quake II is the series’ highmark, Quake 3 Arena defines what it means to be an arena-based competitive shooter.
Wolfenstein: Enemy Territory didn't have gimmicks. No pay-to-win. Return to Castle Wolfenstein's multiplayer is freeware. Those who tried it got one of the best team-based class shooters ever.