I have a Skag Tiger Cub zero turn with a 19hp Kawasaki engine. They sell them where my wife works. It is pretty much indestructible. Best mower i've ever had and definitely the best engine.
Kohler is good though... better than B&S. I have a Deere with that engine. But no match for the Skag.
<<I found me an old (1989) John Deere with a 17hp Kawasaki. The thing just refuses to die, and when it does, everything including cylinder sleeves is replaceable/serviceable.>>