The Kohler Wellworth and the American Standard Cadet's are not good toilets compared to others.
MaP testing shows why this is the case. This is not to say that you can't get use out of them, it's just not the same as the better ones.
Testing shows over and over again, that they are on the bottom end of the ratings.
Better toilets can be had, that are easy to repair, and look stylish.
It doesn't matter if it's a one-piece or a two piece toilets. Most of these have the same internal parts nowadays.
We're not talking about the funky old kohler one piece toilets of yesteryear.
I had a Cadet in 2001 that quit working after a bit and I had to throw it out.
Something must have lodged in the trapway.
That's one reason I like the sweeping trapways on some brands.
There is less chance of having to throw away the bowl when bad things get flushed, or in some cases not flushed through.