X/HTML5 vs XHTML2

So, which one should I pick for a new imageboard script currently in the making?

>>34

I don't see why that's a bad thing. Until browsers all render everything (including errors) the same way, there's no reason to forgive people for doing stupid things.

Besides, give  me one reason why you would have illegal characters or missing close tags. (User input? Sanitize it, you dumbfuck PHPer.)