Gotta go with Sicks. Sandwiches. Because there are so many different kinds of sandwiches (Italian Beef is a Sandwich, a Patty Melt is a Sandwich, a Tuna Melt is a Sandwich, a Grilled Cheese with Bacon is a Sandwich, a Gyro is a Sandwich) I wouldn’t be able to get too sick of any one thing.
Sicks Ate - BRILLIANT! 
If I had to pick a dessert, it would be a hot fudge sundae, no nuts, no whipped cream, extra hot fudge.
Fajitas. Steak, shrimp, and chicken combo. Including salsa verde and guac. I would happily live on this forever.
Oh, I love steak and kidney pudding, but I like a bit of crust.
I lived for three years on Chef Boy-Ar-Dee canned ravioli. And, y’know, I still like the stuff! I could survive on that for the next fifteen years.
That sounds like a challenge! Time and place, Wallace; Gromit the wonder mutt is throwing down the gauntlet! (Wait a minute, Gromit doesn’t speak)
Were we separated at birth? My thoughts, to the letter; stop doing that! 
Maybe broiled scallops. I’ve never had the chance to eat them very frequently, but I can eat as many at a sitting as are available. Sub sandwich, probably, if it’s an actual NY deli one, not from Subway.
Ice cream.
Or lobster, or crab legs, or MD style steamed blue crabs, or calamari…
I loves me some seafood, but I might give the edge to ice cream, as long as I’m not restricted to a single flavor.
Spaghetti with parmesan cheese. I eat it almost every day as it is, so it wouldn’t be a stretch. Two stipulations: 1) I make the sauce my way. 2) The cheese is either grated from an actual block, or it’s Kraft from the green can.
Off to enjoy my spaghetti breakfast…
Dim sum.
I’ve been thinking about this since I saw the thread title go up. I was going to say there’s no such thing. But after serious thought, I’m going with Nice! Traditional Snack Mix since it’s as close to an anytime, all-the-time comestible I bother with. If it weren’t for that stuff, then pecans.
I love fresh fish. Broiled, baked, blackened. Yum. Could easily eat it three times a day. (Though not for long if I die an early death from mercury poisoning.)
Carbohydrates.
mmm
I love food, but can’t imagine a single class of food I’d be happy eating for two days in a row, let alone for life.
For a broader cuisine? Northern Indian cuisine, hands down… Or wraps, since you can put almost anything in a wrap.
If the stipulations are that I dont have to worry about lactose intolerance, weight gain or zits … then … 'za it is.
Moving this over to CS.
I was going to say fajitas, but I think Sicks Ate nailed it. Sandwiches. What variety! So many choices! Reubens. Grilled or fried fish. Lobster, shrimp, chicken, falafel, steak, even plain vegetables make a great sandwich.
Fajitas are kind of a sandwich, right? Technically, it is meat with a bread-type substance as a carrier.
I didn’t think I’d be the first one to mention this. And I was right!
Put me down for pizza. Even if it had to be the exact same type and toppings, that would be fine. I once went an entire summer eating nothing but pizza for breakfast, lunch, and dinner. I was working in a pizza place between junior and senior years at college, and it was cheaper than actually buying food anywhere else.
McDonald’s burger meals.
Cake/Donuts.
Ice Cream.
Just for variety, I’d have to go with pizza. I’d get sick of anything with less variety, no matter how much I loved it.
And if you fold a pizza in half, it’s a sandwich!
pizza…