What is Smokey's Syndrome?
Smokey's Syndrome is a condition that some "teenage" chickens may develop, the only symptom being somewhat aggressive and unprovoked biting.
Is it dangerous?
Not necessarily, as they aren't really attacking, so to say, just biting a bit harder than normal.
My cockerel...
My immediate thought would be to pick the friendly one, but those can be a bit of a gamble (As OneLostHen so wisely said already), but if you want to be safe def go with the average behavior.
Or, wait until they get a bit older and then assess them again. If friendly is still uber friendly and...