I have noticed a big difference in aggression depending on the type of betta. I have also noticed that sex does not matter. IME I have seen that my veiltails have been the calmer more chillax bettas, with halfmoons coming after. All the crowntails I have owned had been extremely aggressive, but tend to stress more in a community tank. But my crowntails repond more to me and tend to flare and get riled up easier, making them very interesting to watch, expecially if you used a mirror. My halfmoons do the same, but they calm down faster. My crowntails would strut for about an hour after seeing their reflection. But every betta is different, so it is really hard to say. There have been some extremely aggressive veiltails and halfmoons I am sure.