Even with the McRib back in action, I think McDonald's new CBO sandwiches are one of their best yet. I have yet to try the beef version, but the Chicken CBO is great, for fast food. The bacon actually has a bit of substance to it, rather than a thin, limp slice. Caramelized grilled onions, white cheddar, and a creamy mustard sauce top it off. I would really like a chipotle mustard sauce version of this, as I LOVE chipotle. (The pepper, not the chain).