I was looking at what batteries to get for my flashgun and came across this awesome comparison website:
https://lygte-info.dk/review/batteri...comparator.php
It tests the batteries,shows their construction,discharge pattern,etc. Sizes include AA and 18650. The reviewer goes by the name HKJ on this forum:
http://www.candlepowerforums.com/vb/...eries-Included
This site then also shows what batteries are rebranded Eneloops and what generation they are:
https://eneloop101.com/batteries/rewrapped-batteries/
Eneloops tend to be made in Japan,and are known as some of the longest lasting and lowest discharge batteries you can get. As you can see the rebrands cover multiple generations of Eneloops and Eneloop Pros,so some might prioritise power and others lifespan.
Edit!!
I have compiled a list of AA and AAA batteries you can find in the US which are Eneloops:
https://forums.hexus.net/consumer-el...ml#post3988841
Here is an overview of some reasonably priced smart chargers:
https://forums.hexus.net/consumer-el...ml#post3988904