I like plastic because when you drop them, they bounce back and rarely break or dent permenantly. You can use them as hot water bottle in your sleeping bag, it won't burn you when you pour hot water in, you can see what and how much is in there and in the rare situation you need to check if something is straight, you can use it as a level.

A seperate cooking vessel is a far better option for cooking. Having something with a handle and doesn't require extra long utensils to scoop things out of is way more practical.