What devices do these AAA batteries fit?

Any device that takes standard AAA cells: remotes, clocks, small toys, flashlights and battery-powered adult accessories. They are ordinary 1.5V alkalines, not a special size.

Are these rechargeable?

No. They are disposable alkaline batteries and should be recycled rather than recharged.

How long do they last in storage?

Doc Johnson does not publish a shelf-life figure. Alkaline cells generally hold a charge for several years, but store them cool and dry and check for leakage before use.

Should I pick these over Duracell or Energizer?

Name brands publish capacity and shelf-life data and are easier to compare. These are a convenient add-on if you are already buying Doc Johnson products, but there is little independent testing to judge them by.