I ordered a Laser that runs on 18650 and another that runs on 16340, both don't come with Batteries.

What is the best site to order Batteries from in the USA? Also, what are the preferred brands to look for?

I looked for 16340 but I keep seeing similar types called such as RCR123A, ARB-L16 16340 700mAh 3.6V Protected Lithium-Ion, etc.

One brand that looked and sounded familiar was Fenix, is this a trusted brand.