For a comfort food, I tend to turn to the simple things that I enjoyed as a child. These two are my most common comfort meals: macaroni with nothing but butter and salt, or cream of tomato soup with saltines.
I would be hard pressed to pick a single favorite comfort food, but I guess it would be scrambled eggs and fried potatoes. My mom always made that for me when I was sick, or as a special meal when she and my step dad were having a meal she knew I didn't like.
There's no way I could pick just one. At the top of the list would be macaroni and cheese, eggs and potatoes with lots of cheese, spaghetti with garlic bread, and pretty much anything grilled.