I've got a lot of experience in this area - 30 yrs.
Miele makes the best units. Period. Though the seem to have an inordinate number of issues in CA. I think it's the water , but can't prove it.
Bosch makes some very good units too. They make some crap too, so they can reach the price sells dishwashers crowd at the BORGs. Most of their USA models are made in the USA but there are a few still made in Germany. They also make the Thermador units and Gaggenau is in their fold too. Those units are made only in Germany.
Miele is going/ has gone to a large detergent pod that dispenses soap as needed. Very convenient except when you run out and don't have one on hand. You can't just run out to your closest store and get one. The good news is they also include a regular dispenser cup so you can use generic powder or tablets.
Be aware that Mieles are 60cm wide. Which means they are narrower than your current opening by 3/8". Not a prob. if you're getting new cabinets, a pain if you aren't. They make compensation plates in stainless, black and white - but they have to be ordered separately ($60 ) and most dealers have no idea about them.
Bosch's units are also 60cm , but they've designed a gasket system that comes from the factory for a 24" opening. It's easily removed if you have a 60cm opening. This also means a Bosch is not roomier Like batmanimal states.
Their third rack is a tad deeper than miele's standard offering which allows for taller items to be placed there . Think ladle ect.... But, Miele's higher lines have a 2 tier top rack that allows for even bigger items than the Bosch. Miele's racks tend to be more closely spaced which means more plates can be loaded but some thicker handmade ones won't fit. At the end of the day the wash tubs are the same size/volume. Remember it's a zero sum game. So, if a super jumbo xtra large ladle will fit in the top rack - that means the height of things that are placed in the middle rack have to be shorter.
People need to be aware that all European brands have trouble drying thin faceted plastic like tupperware and sippy cups. They use condensation drying (super hot rinse + metal tub) instead of a baking element like American models of yore. They'll dry smooth flat plastic plates and mugs just fine. Anything plastic that allows for a puddle of water to not drain will still be wet. You MUST use rinse aid in these units - either in its dispenser or via your tablet/pod/ect.... Also, don't rinse your dishes before loading them in your dishwasher. It wastes water and modern detergents attack that food instead of your china and crystal. They also require periodic maintenance - the filters in the bottom of the tub need periodic cleaning.
Kitchen Aid has been going downhill ever since Hobart sold them off last century.
Cove has a very nice product, but it is very new in the market. I know of too many warranty claims in my circle for me to recommend over Miele or Bosch.
Fisher Paykel single drw. is fantastic in a bar as glass washer. Most issues I've run across were installation related. The double drawers seem to be love hate with people. My BIL just got rid of a fairly new one because they hated the loading scheme and could never get everyone onboard with which drawer was clean vs. dirty.
