There are 2 of us vaping in the household, living in middle of nowhere Canada so I have to find and buy batteries and gear when I can. All my batts except for a couple I bought a loooong time ago are Efest and through co-ops
I have in rotation:
@12 - 18650, mostly 10 amp but also have several 30 and 35 amp in the mix
@10 - 18500, same as 650 with mostly 10 amp but several 35 amp
4 - 18350 I don't like to use these since I can heat them up very quickly in my mechs
Some of the batts mentioned above are over a year old and still vaping, some are also in PV's I didn't check.
Now my reserve stock is what shocked me a bit, since I just buy without really looking at what I have. These are brand new, still in the boxes unused:
14 - 18650 10 amp
8 - 18650 35 amp
6 - LG 18650HE2 I have sitting in a mailbox I have to pick up from coop on here.
2 - 18650 30 amp.
They are a mix of both button and flattop but didn't open packages to see.
My 18500 stash:
17 - 18500 10 amp
8 - 18500 35 amp
These are mostly flattop but some buttontop to accommodate our provari's.
I have 10 - 18350 I bought but probably never use.
As for chargers I have a tenergy 2 bay we got with a provari purchase I never use, nitecore I4 I used for about a month before I got a LUC 2 bay and a second LUC 2 bay still new in the box. That LUC been constantly charging batts for me for the last 12 months without a problem.
I'm a coop junkie who likes to buy genuine gear so stocking up with way more than you need since you don't know if something is going to be offered again is the norm. All my vape gear purchases are through coops, I've not bought any gear from a internet vendor other than juice since July of last year and my wife and I have had nothing but top shelf vape experience and it just keeps on getting better.

edit....those red squares are dense foam spacers I made so batts don't rattle in the battery boxes.