A stove has the advantage of cooking things more quickly and taking less time to set up but takes up room in the pack. A fire wouldnt require you to carry as much but you would still need to pack some things depending on what you are cooking. So which one would you prefer?
Fires are nice, but stoves have an advantage in terms of set-up time, portability and permissibility. I use an esbit burner, and it packs into a very small space, as does its Esbit (or in my use, usually trioxane) feul. Cook in the canteen cup, that naturally packs with the canteen- so very little additional space is taken up. It's also easier to light under adverse conditions. The esbit stove is an item that I found packable enough to keep close constantly last winter, and will probably do the same next.