After reading some Jerry can horror stories (mostly rust and paint flaking off inside and fouling engines), I went out hunting for something better. I stumbled across this page which has some really nice looking cans. They're a little pricy, but they appear to be hardier than some of the Cheaper-Than-Dirt specials. And the spouts they sell look quite a bit more beefy than some of the other ones I've seen advertized around. Might be worth looking into if anyone is in the market.
I just use my cheapo 5 gallon gas cans I got at rural king. I think they were 12 bucks or so after tax. After a tiny bit of tweaking, they will dump the gas out as fast you want.
Those are just plastic, right? I've got one like that with the spring loaded spout. Seems to work okay except there's no pressure relief of any kind. The thing is either bloated from sitting in the sun or sucked up in the cold (with similar effects when traveling at varying altitudes). As long as it's in the bed, I think plastic is fine. Once it's mounted outboard, I'd be wanting metal, I think. If my paint is any indication, anything mounted outboard needs to be brush resistant.
Edit: Mine was also free on the side of the highway, so there's very few things on the market that can beat that price.
From the factory, they have no pressure relief and aren't very good for pouring. That can always be fixed, though.
Here is one of my friend's gas cans.
7/8" nozzle for the gas to pour from, three little vents in the back of it to let air in fast, and he says the vents will pop open if too much pressure builds up.
If you have that spout on your can, you can just tug upwards on the green part while the can is full. That will cause the lever to go the wrong way. Take a pair of pliers to the little black safety lever thing, and yank that out. Then you don't have to have 3 or 4 hands to work the gas can. You can just lift it up, get it situated, and then press the lever down and it just starts dumping the gas wherever it is aimed.
Get the military surplus scepter cans. They're not cheap, and they're not exactly legal in the U.S., at least if your state requires CARB compliance, but they're plastic, are the size of the steel cans and are pretty robust. I've picked up 3 of them over the years. If you get the ones off Ebay that had diesel in them you have to get new gaskets for gasoline.
Most modern gas cans are all the same design. All gas cans produced in the US since Jan 1, 2009 are supposed to meet the CARB regulations. Thank the EPA for that one.
^ 2nd one down, the "water" jug. best fuel can i have ever used. no chance of piercing it or rotting. handles in the right places. easy to fill, handle, and refuel. dumps 5 gallons in about 30 seconds with the breather valve open.
Those Jaz "water" jugs are nice. Still spendy, though, at thirty bucks. I don't understand why all these oversized tupperware containers are so expensive.