I have about 25 or so roosters here ranging from 10 weeks to unknown age adult. The oldest is a SLW and the next 3 in line are Red Sex Links about 18 weeks old. The SLW is skittish around humans and non-aggressive with my girls and humans, the way I prefer my roos to be. He's an excellent watch bird and will alert to even the slightest threat. The 3 RSLs are very friendly so far, but I have some concerns that their friendliness will turn into aggression soon, but so far I couldn't be happier. They don't start crowing until they hear me walk out to open the coop in the morning, usually between 6:30 and 7:30, but the SLW crows throughout the entire day quite often. Then I have got some austrolorps that are very skittish and will not let me get anywhere near them but they were rescues. And my barred rocks are the most evil roosters I have ever had, but they were also rescues and says nothing in comparison to a roo that has been well taken care of. They peck and will draw blood if given the chance and I can only feed and water them through the fence. They will be butchered in about three weeks, as I have no tolerance for an aggressive rooster.
I agree with everyone else though, each rooster will have a different temperament and personality, but if you do end up with one, you shouldn't feel that you need to keep him if he is aggressive either towards you or your girls.