Another vote here for NATO cans. I have a pile of them I bought about 20 years ago. Most were decades old and well used when I got them, but still perfectly functional. Some have German markings and some have Croatian, and the newest are now about 30 years old. I have never had one leak, even when lying flat in the hot sun. I'm sure they will outlast me.
I recently bought 4 new cans made by Gelg in Poland. They claim to be a NATO supplier. They are visually nearly identical to NATO/Wavian cans, but on closer inspection they are not as good quality. They are over half a kilo lighter, so obviously made of thinner material. NATO and Wavian cans both weigh 4.4k, and the Gelg cans weigh 3.8k. And they just aren't as nicely made. I'm sure they will work just fine, but I won't buy them again.
Good to know about the Gelg can.