Well, the output is usually governed by the driver, so in many lights having a high drain battery won’t necessarily help anything when compared with a more standard cell. If the driver will open the nozzle and really let the water flow through the hose, then those high drain batteries can deliver the juice needed and not suffer the effects of internal resistance and excessive heat buildup.
Are there particular light models you’re going to want these for?
I have zero experience with the 26350 but it always pays to look at HKJ’s excellent tests/reviews to see if he’s done the one you’re looking at and then to compare with the others.
https://lygte-info.dk/review/batteries2012/Common18650comparator.php
You can pick the current(s) shown on the graph by using the checkboxes. On the 21700 you’ll see that the Moli and 40T are darn near the same performance up to around 10 amps….the Moli being slightly better at very low currents and the 40T edging ahead slightly above 10 amps. For the most part they’re the same. The Sony is very similar but just slightly more voltage sag than the other two throughout the current range. I have yet to see the Sony 21700 for sale anywhere but I wouldn’t mind picking up a few sometime. Actually I’d love to get the Samsung 50G instead if those ever appear. I’d say whichever you find that has the lower price should be fine unless you’re sure the light(s) are capable of asking for greater than 10 amps of current from the cells. The Lishen is also good, but I’d shy away from the LG models and if you were to pick one from Vapcell, do so very carefully after checking the tests (they had some excellent ones and some cruddy ones, plus several mediocre models).