An interesting topic, and I would like to point out that it depends on which situation I am in, If I am chatting with my mates, i tend to speak colloquially as in 'you lot' if I am speaking formally, it tends to be 'all of you'. I will never stoop as low as reffering to multiple people as 'you's', as I hear a few people say to me 'How you's all getting there', it just sounds wrong in the same way 'y'all' sounds wrong, at least to me that is, but i can respect that peoples accents greatly affect how people phrase things, so i am glad people from different areas speak differently othrewise it would be boring.
'You lot' is what I use most commonly.