The Union sound guys who do televised american football did a little shoot out to see which AAs were, indeed, the best. The found Kirkland (Costco store brand) alkalines to be the longest lasting. Kirkland brand is made by Duracell or Energizer so they are already good, but the Kirklands don't sit on the shelf as long as the name brand so they are fresher.
Only thing better than that would be lithium disposable.
