What are your goals? Why do you want any rooster? The only reason you need a rooster is if you want fertile eggs. Anything else is personal preference. Nothing wrong with personal preference, that can be a strong motivator. I suggest you keep as few males as you can and still meet your goals. That's not because you are guaranteed problems with more males but that the more males you have the more likely problems are.
A big factor with the number of males is how much room you have. Sometimes multiple males can coexist in a flock without any real issues, sometimes there are serious issues. The more room you have the less likely any issues are going to be serious.
I'm not a believer in magic numbers for chickens, rooster to hen ratio or anything else. Some people keep one rooster with one or two hens and don't have issues. Some keep one rooster with over 20 hens and still have barebacked or over-mated hens. Some roosters have troubles keeping a half dozen hens fertile, many can keep over 20 fertile.