It's widely believed that cockerels are loud and aggressive. While the former may be true - I personally love their crows as it's a true sound of the countryside - the latter is not. Like all animals - and humans - they vary from type to type. The vast majority I have come across are true gentlemen, looking out for their hens and leave you to carry out your duties in peace.
However, cockerels are usually aggressive towards each other if given the opportunity; so please be aware of this if keeping more than one in your flock.
Adding cockerels to your flock will not only add splendor to your garden but also provide many additional benefits such as:
Looking out for danger and protecting his girls
Alerting the hens to food and other treats
Decreasing the pecking order squabbles between hens
Fertilising the eggs should you wish to hatch yourself
They are stunning to look at and extremely charismatic
I cannot advocate them enough, but that is my personal opinion.
If you are interested or wish to further discuss keeping a cockerel, please get in touch.