For me, sandwiches of all types are one of the greatest things ever. And I've eaten so many kinds of them throughout my life that I couldn't begin to forumulate an answer. That doesn't even take burgers of all kinds into account.
Seriously, I believe the hand-held food groups - sandwiches, burritos, wraps, hot dogs, burgers, et cetera, et cetera, et cetera - represent one of mankind's highest achievements.