Some friends asked me to make them flashlights.
they asked for batteries as well. After some research i came to these 2 batteries (kinda best-bang-for-the-buck thing):
panasonic ncr1865pf or samsung inr18650 29e. both 2900mah batteries.
as they both cost about the same, which batterie do you thinks is the best for running a XM-L2 U2 @ 3A with a 105c driver
The Panasonic is better all-round. See the above link and find the cells. Note that, I couldn't find the NCR18650PF, but did find its older sibling, NCR18650PD and the Panasonic wins out.