For out BLF drivers the chart( lumen output) would be:
VTC5A- definately the leader, then VTC6/VTC5, then LG HG2/Samsung 30Q, Then 25r/HE2(4)
personaly i use Samsung 30q cause ithave the bet of both sides: lumen output vs runtime
yet for the max amps VTC5A: even at 3.4 battery voltage it gives 2.5amps( vs 2.1 for 30q) at the emitter( XPL)
Wow, I got an overload of information here, very useful indeed. I am overwhelmed with the replies I received plus some really helpful information with regards to types of batteries, ampere, chart comparison. I will try first the Samsung 30q first, then other high drain batteries later. How about keepower high drain batteries? Would you guys recommend that? Thank you very much for helping a newbie here! 
Which Keeppower high drain batteries?
If the black 3200 IMR, which I also have, it is basically a rewrapped of grey Panasonic NCR18650BD, which is rated for 10A continuous discharge.
If that is the case, the Samsung 30Q, LG HG2, Sony VTC6 are theoretically better for high drain usage as they are rated for around 20A continuous
I think the ratings can cloud the issue sometimes. Just because a battery might be rated to deliver ‘x’ goods, does not mean it will actually do it, or perform as well as another battery below this level.
Logically you’d think it should, but inn my experience it just doesn’t seem to be the case. Also pushing batteries harder will generally get the worse performance from that battery, i.e. pushing a battery to 75% of it’s rated draw will normally result in lower runtimes and probably reduce the number of times you can recharge it.
Anyone who is familiar with the RC world, be it planes or cars, will know the discharge C rating of batteries is crucial for performance and is generally much easier to see than it is with flashlights. e.g. a plane may require a 20C battery for it’s rated specs. They supply a 25C as standard. It goes fine. You buy some new batteries which are 45C rated, so logic would say over the top and not needed. But low and behold the plane will be far more punchy and usually fly longer, even for the same mAh rating.
Thank you for your clarification regarding keeppower, so they are rebranded. Okay, ill just buy the Samsung 30Q first, anyway, does the flat top 30q fits perfectly with the Astrolux S1/BLF A6? or it should be the button top?
Basically batteries brands such as Keeppower, Obtronics, Efest, AW are just rewrappers, and same goes for torchlight branded batteries such as those made for Nitecore, Olight, Fenix, etc.
For 18650 batteries, they are normally just rewrapped of cells made by Panasonic/Sanyo, Samsung, LG or Sony.
Flat top works fine, as I’m using the stock 30Q or HG2 for my BLF A6
Okay, so basically which performs better 30Q or HG2 or they are just virtually the same? Thanks for the tip akhyar!
I couldn’t notice any difference through my naked eyes.
Did you also spring bypass mod your BLF A6?
Nope. Mine is stock config
I use flat tops in mine, although I see no reason why a button top wouldn’t work too and would allow it to work in lights that require them. That said, batteries are fairly cheap, so don’t sweat it too much. Just buy for now and worry about later when it happens.
Likewise, the 30Q might or might not be the best battery, really depends on what you consider as best. But it is a good battery for the money and ones that exceed it in performance for this type of light are only going to be marginal. And something you’d only be able to tell by measuring it with a DMM or lux meter, not with the naked eye.
Yeah, will definitely buy 30Q flat tops. I am just wondering why did the Astrolux S1/BLF A6 is advertised as “1600 lumens (use 18650 battery)” I saw it on several websites, whereas here in our precious blf forum it should be the higher Amp/discharge rate / high drain, whatever you call it therefore go for the unprotected high Amp rating batteries for the maximum output. So for a newbie like me, It makes me so confused.
Honestly, you would not notice the difference in output with the naked eye between a GA and a 30Q.
I actually just happened to be playing with my S1 today and was trying to decide what battery I wanted to keep in it. I tried them all and the HE2 still put out the most lumens at right around 1600 (springs bypassed). The 30q was just slightly lower, (I think the exact starting voltage plays a bigger role then these batteries, although the HE2 does generally give me a slight edge).
The GA’s on the other hand still gave me 1450 lumens, without having 2 of them side by side you would not notice the difference.
So basically what I am saying is you can’t go wrong with any quality latest gen battery now days.
HE2 or 4
30Q
MJ1
GA
HG2
VTC5 or 6
ect
^ Well that’s nice to know, so basically HE2 is one of the batteries that would bring the most output for our precious S1/A6. Thank you for the helpful input! I will just find someone to do the spring bypass mod for my s1 to bring the most out of my flashlight, as I don’t have the capacity (knowledge and equipment) to do the mod.
I wouldn’t worry too much about the advertising claims for this light. Suspect some meaning is lost in translation.
Just to give you a little more info on batteries. I did some further testing. I have the Astrolux S41 (which I highly recommend). It’s quad LED unit, using the same driver as the BLF A6. Mines the Nichia variant.
I’ve not modded this one either, although you could do a spring bypass. But again I’ve not really felt the need, it performs well enough as is.
With the protected Panasonic 2900mah battery I get 6.1amps at the tailcap, so shows the battery can deliver more than the amps it managed on the A6. Which reinforces the fact that rated claims don’t always mean as much as you might think.
For instance, if it can do 6amps here, why did it only manage 3.5amps on another light??? — I don’t know the answer to this.
Anyhow, I also tested the 30Q on the S41 and that does 9.6amps at the tailcap!! So a substantial and huge difference to the Pansonic 2900.
This doesn’t have any direct bearing on your torch, but thought it might be of interest and help you decide.
Dude, after reading this I search for the Astrolux s41, and by the looks of it, I felt the need to buy one. Very good reviews and excellent specs, another bang for the buck indeed! My next light! 
The rating on the battery is only how much the battery can handle without overheating and/or damaging itself.
If you dead short any 18650, even an old laptop pull rated for 2A, you will most likely get well over 20+ amps, although the battery will most likely vent or explode shortly after.
I can put a single laptop pull rated at ~2A into some of my triples or even a Skyray king and pull well over 10 amps.
The amp rating of a battery is only what it can handle safely, it mean nothing for how much is CAN deliver.
Lucky for us, the way LED’s work, it is almost impossible to overload a single battery with a single Cree LED (except the XP-G3). The forward voltage is high enough that even in the S1 a laptop pull will only be slightly over it’s rated amperage.
It will run out of power so fast though that it won’t really have time to damage itself (assuming it was not damaged to start with naturally, I don’t recommend laptop pulls for lights like this AT ALL, just using it as an example).
Like I said above, unless you are building a Paper Queen light, any quality modern battery will work just fine for single emitter lights (and most multi-emitter for that matter). Besides getting numbers I actually use GA’s or laptop pulls in basically all my lights except my show-off lights.
So go for whatever quality cell you can find the best deal on IMHO. That said the 30Q is a great battery with a good balance of features and they can generally be found for a good price.
There is a pre-buy for the Stainless steel version of the S41, the S41S on banggood right now for a heck of a deal. Now is the time to grab one if you want it.
I hate to say it, but suspect the stainless version is more of a shelf queen. Like the Kronos X6 stainless, pretty too look, but weighs a ton. Certainly not pocket friendly at all.
Eh, I don’t really care one way or the other. I have a stainless light and I like how durable it is and don’t mind the weight but also don’t find it to be any better in a practical sense then aluminum.
I like my S41 but I find the S1 to be a more useful EDC myself. The S1 (or a custom built Convoy S2) is much more practical in a true EDC where you never know how or when you would need to use it.
The S41 and multi-emitter lights in general are great flooders but outside of ~200 feet or so you are blinded by the flood. It also takes way more lumens and power to light something up because of all the flood.
For example last night actually I was comparing a triple 219c, Triple XP-L HI and an S1.
While both of the triples are making over 2500 lumens, the S1 looks just as bright due to the much tighter hot spot. In fact it looks a bit brighter if you account for the warmer tint.
The triples are great flooders for around the house but for an EDC I want something that can throw at least 150-200m.
My goal is to get the S2+ I am working on now to 250m of throw.