Mason jars are good except if you're trying to move around with weight...
You can have the jars insulated within a bag/backpack, but still, there's a danger they can clink around and make noise, especially if you're carrying more than one jar.
I mean, honestly, unless you're planning to move a large quantity of weed past stationed police officers or through an area where there's a lot of security personnel (I'm thinking of an airport, but it doesn't have to be an airport...), in other words, where someone would be 'on the watch', if you will, for the smell of weed, then plastic bags are the way to go in my opinion. Sure, it smells some, but they don't make any noise and they work as advertised.
Along with that, if you're paranoid, just wrap all your bags in some dry towels, maybe even throw some old plastic shopping bags in your bag or whatever to insulate the weed smell...that's just my practical opinion. I understand that jars are more effective in containing the smell but they make too much noise for my taste...more people would be able to hear the jars moving around than being able to smell the weed (unless you're talking about a pound or more or some shit, which, by that point, is going to be hard to totally block the smell regardless...).