I vote for low one piece kohler, I bought two for my mom's house one was a low model super quiet and never had an issue, the other kohler was a taller one piece super loud on flushing and filling but kohler doesn't make internal parts you get a generic one made out of plastic not brass... My girl has a top of the line toto, and I hate it doesn't have any power to flush, weird shape inside the bowl and hard quiet but takes a while to fill, also has a leak and I cannot figure out the way to fix it, (inside the unit not leaking out) to clean. I bought a cheapo from orange box for 100 with a California rebate it was zero minus 9 tax... I thought that was good, two piece not bad looking... forgot the name you'd notice if you went there.