I'd just add a layer of aquapanel, bedding it on flexible tile cement, and screwing into to the joists every 150 or so once it's gone off. Then use a proper cement-based flexible tile adhesive (eg BAL, Ardex, Nicobond etc) not one of the ready-mix glues - these aren't particularly cheap, but it ain't that much in comparison with a failure.
Either seal the grout, or use epoxy (don't listen to whinging pros who say epoxy is impossible, it's just a bit irritatingly sticky and slower, but perfectly easy to use).
Tile is a fantastically practical surface in a kitchen - unlike wood or stone, it won't stain, and you can mop it and it won't rot. And it isn't plasticky vinyl.