When it comes to canned tomatoes, I used to buy whatever the recipe dictated. I figured the only difference between, say, crushed or diced was the size of the pieces — but I did what I was told, as to not mess up the dish. Then one day I had a recipe that called for both whole and diced. Without questioning I diligently bought both, opened them up, and was shocked by how pale and watery the diced tomatoes were in comparison to the whole. Same brand, different preparation. Clearly, it wasn't just the size of the pieces that were different.
I don't know anyone who has ever worked in an industrial tomato processing plant, so I can't say for a fact that only the premium tomatoes get canned whole, while the inferior fruits and trimmings get processed into everything else. I do, however, have my own anecdotal evidence. Plus, many other home cooks agree, and even the processors must admit that there's a grading system. And that's not the only reason why, for me, whole is the only way to go.
Why I Only Buy Whole Canned Tomatoes
1. It gives you more options.
A can of whole tomatoes can be turned into anything else — diced, crushed, puréed, sauced. So if you have a pantry of whole tomatoes, you're good to go. On the other hand, you can't make diced tomatoes whole again.
2. You can pick between juice or purée.
Whole tomatoes come packed in juice or purée, giving me two versatile flavor options. If want a bright, fresh tomato flavor, I'll pick juice-packed. If I want a richer, deeper flavor, I go for the ones packed in purée.
3. They cook down better.
Diced tomatoes have calcium chloride added, which helps tomatoes retain their shape, even during cooking. Maybe that's a boon to some cooks, but I'm just not a fan of big chunks of canned tomatoes in my dishes. For what it's worth, most American-grown canned whole tomatoes have calcium chloride too. If you want to avoid it, like I do, look for an Italian import.
4. I always know what I'm going to get.
Crushed tomatoes are unpredictable. With some brands they're crushed almost to a purée, while other brands might still have big chunks. Whole tomatoes are just that — whole.
5. I can season them myself.
Canned tomato sauce (not pasta sauce) and stewed tomatoes have too many other things added — herbs, spices, sugar — to make them truly versatile. I'd rather purée my whole tomatoes and season them the way I like.