Anytime I make a kit that I 95% of the time won't be carrying in a pocket I choose to go with a metal mess kit style container that allows me to cook and/or boil water in. My kits are either Mini or Medium. Nothing really in between. I never skimp in quality either.
I like the mess tin based kits aswell. Plastic is nice for waterproofing and protecting but doesn't have the ability to cook in.
I have the actual military mess tin and tried to make a kit like "lofty" in the sas survival guide but some of the items are obscure and not avalible to me. When I use my own choices its always overflowing.