Built-in ovens (not one, but two) would be in my dream kitchen...if you have the counter space, I guess putting it on the counter has advantages. One that comes to mind is that if you want to sell, the buyer isn't restricted to the size of microwave you have. The other is that if a person has mobility issues, it is easier to get things out of a countertop microwave than one that is mounted. Another is that srs/elderly people may have problems lowering and lifting things out of a microwave that is mounted. My brother and I have tried to get our parents to put their microwave on the counter because my mother has restricted use of her left arm. But because it is built in, we can't get our father to agree. If the microwave had been on the countertop to begin with (they built the house), this wouldn't be an issue. A little vision goes a long way.