I've used all three in my home.
Champion bowl "depth" could be better. If the fill tube is positioned between the two lines on the flush valve you do get more water in the bowl.
It's very heavy. The ADA version may not fit under the hand rails. (made in Mexico)
The first version of the flush valve had problems. This is a very new model so it's hard to say if they got it right. The first I had heard of it was August 2003. Mine was installed in Winter of 2004.
Cimarron flushes well, though some of the bowl is missed by the rinse from the rim. Keep a brush handy with this one. (made in Mexico)
Vacuity will leave particles in the bottom of the bowl often. They have had some problems with plugging. I gave mine to my brother for his cabin, but he wound up throwing it away after a few months.
Toto Drake, the one that the Champion and Cimarron is modeled on is still the best. You won't find it at the home center, though many plumbers have them. The basic design is over 10 years old now, it first started with the Ultimate, and then an upgrade to the Ultramax.
Of these I'm selling hundreds a year, many to the same customers and to their friends. I get a lot of calls when they move to newer homes. (made in various places, Atlanta GA, Japan & China) They are the largest plumbing manufacturer in the world. They are the Lexus of plumbing.
Most repairs in the tank can be done quickly and without tools. The fill valve and flapper are made in the US by Lavelle/Korky.
This week I sold a Drake to someone that had tried the Vacuity, after his third probmatic Vacuity in the same bathroom he wanted to try something else.
Terry Love's consumer report on toilets
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