The real answer is Roadblock.

But I chose Cobra Commander. Destro I'm never sure about. He's in theory too smart to hang around Cobra. But on his own, he loses that interaction with other Cobra agents. I don't want him as a good guy, either. He might respect the joes, but his interests almost always run counter to theirs.

Zartan is overrated. The more ninja-connected he got, the worse he became. Dreadnoks dumped for red ninjas? Giving up evil?

Hawk...for nostalgia, I like him, but honestly his role can be filled by anyone, actually. And probably someone more interesting. Character wise, Hawk is often too much the ideal boss/leader. In early comics he had an edge, maybe dark side hinted at. later on, he was Captain America uncostumed.