after comparing several cells myself - and also comparing hjks reviews - i find that efest imr v2s, aw imr, and kinoko imr work best for me
eagletac, trustfire flame, xtar and nitecore 16430 all do ok, but have much more voltage drop and less capacity if used on the higher modes that demand 1-2 amps and sometimes more
the best of the best as far as holding voltage appears to be efest 16340 per hjks tests, with aw and kinoko right behind
they are all +/- 500mah
richard sells efest v2s for a good price Efest 16340 V2 IMR 700mAh - Button Top