Toilet Flapper HELP experienced landlords

[Shawn M.]

Does anyone know of a good universal replacement kit for the toilet guts? Seems like the only repair calls I get are for broken flappers and toilet handles. I've been using the fluidmaster parts from HD/lowes but they *always* break. I'm willing to pay more for a product that will last more than a few years but haven't found any. What do you use?