For value maximization, breakfast is a snack credit, married with a dessert you didn't eat from a QS meal the previous day, lunch is a QS credit, and dinner is TS.
However, different things apply for convenience and other reasons. For example, on a recent trip, my family found the following to be helpful to our trip enjoyment, even if it didn't maximize "value" compared to cash price:
4 of us would use 2 QS credits at breakfast at the resort. The breakfasts were generally way more than any of us would normally eat for breakfast, so this worked fine -- a couple days, we supplemented with a snack. The drinks would be bottled drinks that would come with us to the parks so that we wouldn't use snack credits on drinks.
We often used TS at lunch because it was easier to get ressies for places we liked. This was particularly true as we changed up our plans from time to time on the go, and we were there during Xmas/New Years, so everything was pretty crowded. This led to QS at dinner, which was also a plus when in the parks, as the QS places are much less crowded at dinner.