Real food whenever possible. I started hiking with bars and goos and freeze-dry, and always found them disappointing. I like having that hunk of cheese, some hummus and crackers, fresh baby carrots and canned chicken to throw in the instant noodle soup on a backpack, juicy grapes on hot day, a big honkin' sub for an uber-hike, etc. My body gets the calories just the same, but I find myself much happier and infinitely more satisfied. I like variety, and taking a snack each of the different items gets me that. Different-flavor bars can only go so far.
The only time I haven't taken real food was our 5-day backpack in Colorado. We survived on freeze-dry dinners and turkey jerky, and una_dogger ate a lot of bars. It was certainly useful to have all that lightweight food, and easier to deal with, although at this point u_d doesn't even want to *look* at jerky any more. For a northeast backpack, though, I'm going to take some real food for at least the first few days.