Yes well I was assuming a decent sized kitchen.
But even 14x20 is considerably more spacious than 12x17, and even an 18x 24 will sit nicely enough atop a standard microwave, of course you'd probably want your counter to be at least 24 wide.
Extra free length on the counter isn't so important as you have a table, stovetop, etc for your mise bowls.
I do feel my 14x17 is a little dinky, but when you consider the whole dynamic it's tolerable as I said.
So of course sizes are debatable here.
Speaking of JK Adams, this one's end-grain, Cherry, nicely thick [for an added margin of durability against possible defects], 18x18 and a decent price. https://www.jkadams.com/collection-35