with bantams, attitude/feistiness depends on the breed. i have bantam cochins and faverolles in with my LF faverolles and i have a D'uccle. the 'D'uccle had an attitude but for him it has been seasonal, and others i've owned of his breed have been docile and hardly a problem. with my bantam faverolles i've never seen an attitude, the cochins i've occasionally had one with a diva attitude, or in the case of the young cockerel a feisty little brat. those boys don't last long in the flock and the girls usually settle down after some time.
i didn't care for bantam Wyandotte when i had them in my flock. they were mean to my other birds and louder too. but the person i got them from said they were hatchery so i blame the 'tudes on that.