I use Scepter MFC gasoline cans but I wouldn't say they're the best ever. I went with them originally because my Blitz cans were rusting, which I didn't like.
Scepters swell and contract, they will weep a little. So a couple of things I find are important if you do find real military (the consumer Scepters are totally different) ones to use.
One is having Specter model 4856 fill spout. This thing will empty the 20L in maybe a minute or so.
The Scepter Military Fuel Can (MFC) pour spout was designed to fit on both the 5G / 20 L and /2.5G / 1L MFC. Ideal for filling onboard tanks.
scepter.com
The other thing you need with Scepter MFC cans is better seals. The factory plastic cap flange breaks and even when it's good they weep. The JAGMTE aluminum one is infinitely better.
Finally! The LAST FLANGE YOU WILL EVER BUY! Bullet proof your Scepter Military Fuel Can. This flange makes the Scepter MFC what it always should have been. An extremely durable, dependable and worry free way to transport fuel under harsh and demanding circumstances. The flange is milled from...
jagmte.com
Add his cap wrench and you will never get leaks or weeping nor will you ever get a case where the can has cooled and the cap is locked tight from the vacuum.
***IMPORTANT***This is for the Military FUEL cans and will NOT work on the military WATER cans. WATER WRENCH is available HERE. The Original M.F.C. Cap Wrench — precision-fit for Scepter Military Fuel Cans Stop fighting swollen cans, fouled threads, and over-tightened caps. Our USA-made MFC Cap...
jagmte.com
At this point since Scepter MFCs not being blessed by the safety overlords make them expensive, add in the need for the upgrades. It's an expensive proposition.
I have a couple of Wavian NATO cans around that I got recently. As cans go they're probably better. You don't need special caps and wrenches to keep them from leaking. I haven't really used them other than garage storage because my carrier is sized for the Scepter and the Wavians rattle around more.
Not sure about spouts. Got a Valpro like I guess the British military uses and it seems to work pretty well but I still prefer the Scepter spout.