The extent to which the "ya'll" vs. "y'all" debate still rages illustrats how unresolved that debate is. Again, both spellings are common, even with the most widely respected authors. The word itself is informal and colloquial, and its origin is as uncertain and contested as its proper spelling; it is impossible to definitively say whether it derives from "you all" directly or via intermediate "ya all." That is part of why the debate rages on with no clear winner.

The question (perhaps I say it as should not) is whether it is enough to be right or if others must also be WRONG. If you want to spell it "y'all," fine; I have no objection (though others, including many Southerners outside TX, do. ) Debating whether a word that was never part of the Queens English in the first place MUST be spelled that way and no other... well, yes, your time is probably better spent aiding the imminent Squirrel Apocalypse.