Personally, I have never had a people aggressive JG rooster. and honestly, in 25 years of birds, I can only think of but a handfully of roosters that were hard core aggressive.
My Giants are fairly laid back, but do well in a mixed flock. If you are getting only one rooster, any from the three breeds should be relatively calm. Handle him when you get him, and things should go smoothly.
Frama
Talking to a few people are here has given me serious rooster anxiety!
