BLF A6 - short tube Which battery?

Want to order a short tube + o rings for my BLF A6. Which is best battery brand & style, flat/ nipple top etc to buy for the short version?

bump

18350 Efest purple IMR, AW Red IMR, Keeppower Black IMR.
Button-top or flat-top works fine for me

I’m using AW Red button top… works great.

thanks peeps.

IIRC my red trustfire imr pulls a little more amps than my keeppower imr.