More than a particular food, I wish companies wouldn't play with successful formulas, invariably ruining them.

McDonald's with seed oils.
Good n plenty with thin shell.
Coke with hfcs.
Snickers with sickening sweetness.
Ben n Jerry's with their ridiculous graveyard.

I do miss Taco doritos, but the fact there is so much toxic crap in them, I suppose that is a blessing.