I've been into electronics for 40 years.  The cost of batteries has had me try many different brands, and types.  I use some rechargeable batteries, they are not always the best choice.  For the battery sizes of AAA and AA, I look for a cost per battery of about a quarter. It is important to purchase Alkaline batteries at a minimum, don't get the cheaper, Heavy Duty batteries.  They leak more, don't have the shelf life of an Alkaline, and product less power.

Since these are Alkaline batteries they have a long shelf life, 2 to 4 years is typical.  The package I am replacing shows a use by July 2016, which is over 3 years away. Here's what I am currently using for both of those.

For AAA batteries they come is a 36 pack at about 23 cents per battery. ($8.79 as of this writing)

Odd note of interest, years ago I checked Alkaline batteries for maximum current output.  These devices, no matter the size AAA, AA, C, or D, put out 5 Amps maximum.  Apparently the chemical reaction used to produce the power is the limiting factor, rather than the size or capacity of the battery.  That means if you have to use AA batteries in a pinch to replace "C" sized batteries, if you can get them to stay put, they will work fine. Albeit for a shorter amount of time.  Of course as always, all batteries in a device should be the same type. Goofy things happen if battery types and styles are intermixed.