Recipes seem to be split down the middle of whether or not meat to make jerky should be cut with the grain or across it. What is the difference in the final product when cutting with vs across the grain?
For me it very much depends on what meat I am making jerky out of.
With the grain is much more solid than against. Just as you might expect.
If you are using relatively tender meat then cutting across the grain will result in a batch of jerky crumbs. Cutting with the grain will be good.
If you are using very tough meat then cutting with the grain will be absolutely impossible to chew.
I often make jerky out of brisket which is very tough. I compromise and cut at a 45deg angle. This results in very tough, jerky but it separates into smaller, more manageable chunks when it is chewed.
I do it both ways in a single batch. If you cut across the grain you end up with a more crumbly product. It's easier to bite off say a quarter of a stick of it and chew it. If you cut with the grain, it's chewier. It may be harder to bite a piece off neatly. It tends to take longer to eat it, which for me is a feature, not a bug. (When canoeing, I like to put a piece of jerky in my mouth, half sticking out, and as I work through it, it all gets eaten. The crumbly pieces sometimes break and half ends up at the bottom of the canoe, which is a shame.)
Rather than get all worked up about it, cut roughly half each way, according to the shape of the meat etc. Then people can choose a piece that they like. (For the same reason, I cut pieces of varying lengths, too. Even the thickness of each piece doesn't have to be identical - thinner pieces will be more brittle when you're done.)
After you've done your first batch, if you find you strongly prefer one kind to the other, you can do them all the same from now on. The differences are more pronounced in a really grainy cut like flank, btw - the only cut I use for jerky, ever.
Good advice so far but for a new person into jerky making I assure you that no written answer will totally satisfy you. You must learn by trial and error yourself. Written answers are great guidelines and tips but which meat and directional cut is a personal preference. I prefer Top Round Steak myself and I cut it each way (With/Cross/45 Degree). Cross grain is cut the thickest (1/4 - 5/16) and the thinest being with the grain (1/8). Different thickness means different drying times. The thinest might only take 4 hours in dehydrator and thickest might take 10-14 hours. Many factors determine how long it takes. The main thing is be safe by temp and a minimal time for the jerky and after that try anything you want. You will probably be very satisfied with all 3 cuts to some extent. The biggest worry would be cutting too thick which makes the outside like boot leather even when the inside is the right consistency. I hope this helps.
Always cut your meat for beef jerky across the grain. If you end up with crumbly meat doing it this way, you are simply doing it wrong or using a poor choice of meat. Your meat will always be more tender cutting it across the grain. If you like your jerky to be extremely tough, then go ahead and cut it with the grain.
I have made jerky a lot and I shoot for 1/8" thick with a meat slicer, obviously that would be difficult with a knife and a 1/4" with a knife would probably be OK. I cook mine at 160d for 4-1/2 hours at 1/8" thick cut across the grain and it turns out great every time.
I prefer the eye of round roast and purchase at Costco for around $25-$26 for between 4 and 5 lb roasts. This makes about 1-1/2 pounds of jerky. I was paying a guy $40 per pound for the jerky he was making; although his was good, that is pretty pricey. Just like buying it in the store. So for $17 per pound, I will make my own and it's exactly the way I like it!