What is a grammatically correct term for "ya'll"?

I am not from the south but have always used this term. It is a good universal polite pronoun especially in passing with men and women when there is either an unknown connection or none at all.

However I have been told “ya’ll” is grammatically incorrect. I can concede that as a conjuction it is informal and probably slang and with roots in the South it falls under the heading vernacular.

But is there any formal replacement and grammatically correct term that doesn’t sound neurotic or awkward?

What word do you use in place of “ya’ll”?