Planet Fitness is like $10 a month and usually 24/7. I'm sure someone will criticize planet fitness because it doesn't have x,y,z...but I don't think you can get better value for an average person.
More likely people might criticize that Planet Fitness does not exist in every country. Or it might not be close enough to everyone. Where I live the cheapest gym membership is 24€/mo and that gym is shady as hell (really bad reviews everywhere).