Diagonally just seems “right” to me.
I also ticked “no crusts” because that’s how I insisted mom make them as a kid, though these days I don’t really require it. (sometimes I will eat to the crust then stop though)
I only make sandwiches occasionally, and then I almost always have them on kaiser rolls, which I don’t cut. When I was young, my mother always used regular white bread and would cut sandwiches horizontally. There was one exception: BLTs. She’d cut these diagonally.
Like SurlyChick, vertically except for grilled cheese.
Diagonally feels like there’s too much crust per inner. At the end you’re left with nothing but crust.
I follow the symmetry idea as well. The bread I buy is generally square shaped loaf; the bakers do something or other to make it more or less square. There is usually very little indentation, so I cut it vertically to make both halves equal. If I am going to take my time and the fixin’s aren’t drippy and messy, I cut it. If it is some honking Dagwood El Grande sandwich, it shouldn’t be cut or be on some form of roll, as others have said.
I’d never cut a burger in half.
I don’t like diagonals. Corners seem like an easy way for somebody to put a razor blade in your sammich.
If I really have to cut a sandwich, I tend to cut it vertically, so the halves are mirror images of each other.
But I rarely cut a sandwich. Instead, I eat all around the perimeter, then the middle (saving the best for last).
I pretty much never cut a sandwich. If I do, it tends to be horizontally, as round/oval loaves of bread are kind of funny cut on a diagonal. If I do happen to have a square-shaped loaf, and I happen to feel like cutting it in half for some reason (pretty much the only time I will is when making a grilled cheese sandwich), then I’ll cut it on the diagonal.
Sideways, through the ingredients, not touching the bread.
…Is there any other way? 
Sounds like you need some square bread. 
I don’t cut my sandwiches. I’m a beefy guy and find that a half of a sandwich is too quickly consumed. So, I’m still hungry when I pick up the second half. In fact, I rarely make just one sandwich. I usually make two.
I’ve never been able to cut them with a spreading knife, and I see no reason to dirty up a regular knife just to cut it. The whole point when I’m going for a sandwich is to avoid having dishes to clean or more trash that will have to be hauled to the dump. Well, that, and being quick, which again is thwarted by having to do an extra step.
The only reason I’ll cut sandwiches is on party platters, for kids, and at diners where they put so much stuff in the bread that it needs to be cut.
Do you guys cut your burgers, too?
I have no preferred method of sandwich cutting - if I’m making them for someone else with square sandwich bread, I’ll usually cut diagonally into quarters - if I’m making them for myself, I might just fold single slices around the filling, or cut in half or quarters on the square.
For sandiwches made with other shapes or thicknesses of bread, I’ll cut whichever way works best in terms of retaining the filling while it’s eaten.
I don’t eat burgers but the nearest equivalent, say a grilled chicken sandwich, I eat with a knife and fork (when available) and cut off a mouthful at a time. I have no desire to get my fingers and face dirty/greasy (you can’t bite into a whole burger without getting some grease around the mouth) when we have invented perfectly good implements to prevent it.
I’m a freak.
Different sandwiches get different cuts.
Turkey is always rectangles. Ham is triangles, preferably little ones from cutting it in quarters. Grilled cheese is triangles.
On those rare occasions when I make my own sandwich I don’t cut it at all. When I get one at a shop or restaurant it’s most often cut diagonally. That may be determined by the fact that if I order a sandwich, it’s most often a cluib and that’s how they tend to be cut around here.
If it helps a little, I don’t do much sandwich making or ordering.
Of the sandwiches I do order I’d say they fall into these categories:
- Burgers – not cut in half
- Subs – sometimes cut in half (midway between the ends)
- Club – diagonally
- Grilled cheese – diagonally
- BLT – diagonally
- deli sandwich of some sort – could be cut anyway or not at all
For ‘normal’ bread, I use a vertical cut. Except for grilled cheese. Isn’t there a law that those have to be cut diagonally? I’m pretty sure there is.
But lately I’ve been buying really dense whole/multigrain bread that comes in loaves that are fairly short for their width. Cutting those vertically results in basically square halves – that is, each half is almost exactly as wide as it is tall – and that just looks unesthetic to me.
So now I cut my sandwiches into vertical thirds. 
I cut my sandwiches vertically. UNLESS I make a grilled cheese. Then I use this:
YUM!!!
And cutting it across through the center gives you 2 half circles. 
I prefer natural selection- I cut it whichever way seems least awkward or most convenient (ie: is the sandwich in a vertical position or a horizontal one? Where’s my hand and the knife? What’s the closest cut I can make w/ the least spillage and effort), and then I eat whichever slice is smaller first. Then the winner gets to be eaten last as it’s rightful reward after it has seen the loser perish.
I do this with ALL foods that are divided. Pizza slices, sandwiches, pies, Chicken nuggets, portions of meat- anything that has been given to me and cut, I use Natural selection on to eat the smallest ones first and then eat the larger piece 2nd.
So I voted for Cutlery Surgery, as I didn’t want to vote for all the various versions.
<< Nothing to do with sandwich cutting >>
This Battle of the Slices reminds me of my childhood in the back yard where we had several pecan trees. Every fall my brother and I would sit down and crack pecans and eat them for what seemed like hours at a time. The game was to use two pecans in the palm of one hand, with the assistance in squeezing them from the other hand, and get one of the two to crack. As time went on, there was usually one pecan that was tougher than the others, and after a while it became the Champ Pecan.
Whenever we got full or tired or bored of cracking pecans we would have a Final Battle between His Champ and My Champ (alternating who got to administer that last cracking) for the Ultimate Champ Pecan.
It was oddly the case that in more than 50% of the cases, that UCP was either rotten or – get this – EMPTY!
<< /Nothing to do with sandwich cutting >>
wow… i always figure cutting a sandwich was just a tv/restaurant thing to show off the food. I have never actually cut a sandwich at home, except when we make large subs.
On a related issue. To prevent crushing a sandwich or shredding the bread when cutting, slice the top piece of bread off the sandwich, then put the pieces back on top and slice through. Very effective on bagels to keep the cream cheese from squirting out the sides.