I don't have any good fuel cans *yet*. I'm suffering with the crappy Walmart cans.
I bought one can, and I've used it once. It's one of the kind where the spout never gets stored inside the can, it's got the seal on the end that you have to try to open, and it has no proper vent, but has the vent tube inside the spout.
After the first use, I realized it was a complete piece of garbage. It takes about 10 minutes to get all the fuel out because it's so slow because of the crappy vent design. And I ended up spilling tons of gas all over the place. It's just worthless. So, $10 for a can that got used once. How expensive is that?
I have 4 other cans I bought a little earlier, these are the type where the spout does store inside, but there is still no external vent, it has the vent tube inside the spout. These are also slow, but not as bad as the previously mentioned one. They also leak all the time, and I can't store them in the vehicle for long. I do use them, but I hate them, and long for the days of external vents.
The old plastic cans from 10-20 years used to be ok. But you can't buy a good can anymore. CARB is MMMMed in the head if they think these new designs are better. I've never spilled so much fuel as with the new ventless cans.
I've actually been wondering though, what do Jerrycans do for a vent?