Large seeds store better in nitrogen. On the other hand, small seeds, like many garden seeds store better in air. For this reason Walton cans their garden seed packs in air. Whatever container you use, be sure it is food grade as your product can be tainted with whatever the container is made from. Plastic sacks are not good air tight containers, for even if they are sealed, the relatively thin plastic 'breathes,' allowing air to pass through.
Paper sacks are of course even worse.
There is some concern as to how good a seal is made by the lids on plastic buckets used by food storage companies. Manufacturer studies show an extremely small amount of air transfer. This amount is so small, however, that it can be considered a hermetic seal. It has also been found that the lids can be re-used several times without dramatically degrading the performance of the seal. People who purchase products from food storage providers are often concerned about receiving their buckets bulging or with one side collapsed in.