I have to say that I'm impressed with the McDonald's Third-Pound Angus Mushroom and Swiss burger. I'm usually not a fan of McDonald's food, and I typically prefer Carl's. But, the Mushroom and Swiss burger has me coming back for more lately.
It's clearly not a great burger, but it's surely a great burger for its price and for what it's meant to be (a fast food burger). I prefer In 'N Out (who doesn't), but when you're craving a mushroom burger, I'd say it hits to spot. Give it a try.
I'm planning on trying out the other two varieties in the near future. In any case, I hope McDonald's keeps the Mushroom and Swiss Angus burger on its menu.