They are beautiful, they are noisy. They are a natural member and usually leader of a flock, but the hens will be fine without him - generally.
If you free range, I would suggest keeping a rooster. He will give his life to protect his girls. A common ratio is one rooster for every 12 hens.
If you have lots of room, I'd keep a rooster or more depending on the size of the flock, yard and property.
I've kept chickens for many years. I moved a few years ago and started a new small flock about a year ago. I decided just to keep hens, as I don't want chicks and don't want to subject myself or my neighbors to the noise of a rooster.