Best or Better 21700 Battery?

I'm new to the world of 21700 batteries. Which batteries are the best in terms of performance and which are best in terms of 'value' (cost for performance)?

Are the ones with built in USB-C charging as powerful and reliable as stand alone batteries that need an external charger? Which batteries and charger is best if you don't use the built in charger 21700's?

TIA,
Sid

p.s. Yes, I did search and found a lot of flashlight threads but, not really anything regarding the batteries themselves except for people pro/con with Tesla or wanting something smaller. Cost and form factor seems to make the 21700 a great option for normal flashlights but, I'm really new to the batteries.

One factor --

WHICH flashlight are you planning
to USE them in ? ? ?

Need to know the Maximum Current
your needs require.

Look for something based on the Samsung 50E cell, as the cell Fenix includes or recommends seems to based on that base cell.

I personally have two of those, awesome capacity and decent current capacity.

Nitecore makes a 15 amp rated 5000 mAh 21700 cell that has usb-c charging.