I have had experience with the countertop, and the roller kind.
The floortop, I guess, that was a little smaller than a built-in, but could still handle a day’s worth or dishes for two people, and rolled up to the sink, was every bit as good as a built-in. We bought it at Goodwill for $18, and it was a superb bargain. It lasted 4 years, and might have lasted longer, but we could afford to install a built-in at that point, and did, because the saved space helped a lot. It did not have its own water heater, but it did handle the water from the hot tap without it damaging the lines, or anything, and since we did not have a child at the time, and also had a small apartment “hook-up-to-sink” clothes wahers, and a small vent-inside dryer (which took twice as long to dry anything, but them’s the trade-offs), we had the water heater turned up pretty high. We were in a rented house,a nd had our own water heater.
It did need to have the filters rinsed out between washes, but that took about 90 seconds. And as long as we did that, we didn’t have to “pre-wash” the dishes, just remove tablespoon-sized chunks of food.
My countertop model sucked. It barely removed food at all. It didn’t heat the water, and it didn’t dry. Eventually, I just soaped up the dishes, stuck them in the countertop to let it rinse, then opened it up to let them air dry. So basically, it didn’t sterilize, like most dishwashers. It only cost $60, but it was a total waste of money.
It’s possible that poor water pressure in the aparrtment where I had the countertop was responsible for the problems with the machine, but I doubt it. It was a mid-range model in regard to pricing.
If people here say they had a good experience with a countertop, please say what range of price you paid. When we looked, the best countertops were as expensive as the floor models, and the only advantages was the compact size. No countertop I saw dried, and even most of the cheap floor models did.