My personal preference is NES -> Master System -> Atari due to the game libraries.
With that said, do you have any favorite games that are exclusive to either console? That might help make the decision. Are you able to gettl the games? I would argue without games to play, it probably isn’t worth it. Do you have the means and ability to repair or make needed upgrades? These systems are getting on in years and I find myself repairing my consoles more frequently as the years go on.