Which is the best aaa Battery for Keyboard / Mouse ?

My BT HP mouse has lasted for more than 280 days with a plain AAA Duracell (not ultra). Similar experience with Fire Stick 4K remote and others. 

Now I just buy Duracell in 12 multipack and stopped buying other AA/AAA batteries. If you have money to spare and are environmentally conscious, try Panasonic Eneloop rechargeable batteries.

All the best

I'm using Duracell ULTRA, really long lasting 

any alkaline battery is fine, energizer

I am using eneloop since 3 years , same batteries still working like day one

Energizer max will last you longest.
Next will be Realme.

These both provide high capacity along with stable voltage.

For Duracell, it's better to go with Chhota Power as its capacity is about 75% of ultra, but price is half, also provides stable voltage, but won't last as long as Energizer Max.

On a side note: If you're okay with frequently changing batteries, try Eveready blue. I saw in a youtube video. It lasts about 60% only as compared to Energizer Max, but price is also only ₹8 per pc. So even 2 such batteries will eventually last longer and cheaper than Energizer Max or Duracell Ultra.

duracell

Bought SmartCell AA or AAA alkaline from amazon for about ₹14/piece effective price (they have min order quantity - buy Amazon fulfilled ones) and quite satisfied.