They are usually louder than most because there is never an opportunity to insulate the tank which is, almost always, the cabinet. I just have a thing for the top-loaders and have found them ridiculously useful. I owned a KitchenAid like this one once and it wasn't loud at all.
As you might expect, I have a bunch of GE top-loaders, built-ins and portables, but only one Maytag and one KitchenAid. I'd love to find a newer KitchenAid, a Whirlpool and I'm always looking for more Maytag WP-600's, the largest home dishwasher I've ever seen.