Dont bother. People in this forums are only interested in talking about multi thousand $ gear. Check, any posts related to using phones or tablet as source are not even read, let alone responded to.
That said, your request is not too clear (at least to me). All tablets are Wifi anyway, and are you asking which tablet has best audio output?
If you're looking for line-out (presuming there that you don't mean USB audio out) then basically all the Android tablets are off the table. If the criteria is decent line-out I suspect you are looking squarely at Apple, although I have no experience with Windows tablets and others might be able to help you out there.