I have never had a problem with my sofirn batteries. I checked the 2 that I have from my HS20 headlamps, which are a year old and one was a few mA over and the other was a few under. I’m ok with that. I just checked my 2 year old anker battery and it got 1 hour into the test with my opus BT c3400 and displayed null. Which was very disappointing.
All my backup batteries are samsung, LG and epoch batteries.
I am glad that you responded to my question. I have been looking on different battery seller websites and unprotected batteries are definitely cheaper, even the high quality batteries are cheaper.
I have a limited budget for my want, not need, purchases every month but with yours and others information, I can now purchase a few more batteries to replace some low quality ones that my sons have.
If at all possible buy only cells from the large manufacturers: Molicel, Samsung, Sony, LG, Sanyo/Panasonic.
On average these will be the best, safest cells.
The 21700 & 18650 I got were samsung and Molicel and an 18350 epoch.