I have no idea what a $100, or even a $40, light is like. I suspect though that unless you have very specific specs/needs, the gap between a $100 light and a $40 light is pretty small, and mostly in accessories that are probably only worth $10/tops.
I’ve got them both at hand right now, and I’d say the BLF A6 and the Zanfare F1 (received ~1week ago) are pretty comparable.
F1 is, indeed, a bit larger than the A6, certainly enough to notice in a pocket. F1’s anodization is a little glossier, but it isn’t clear that it is any thicker or thinner. The F1’s anodization is definitely more consistent — under strong light, none of the pieces on my A6 quite match. The F1’s clip feels less substantial.
I agree the F1s tail switch is a little mooshy feeling, a compromise, I’d guess, to make the tailcap shorter. Given that the switch is only used to turn the light on or off, I think that was a reasonable tradeoff.
The F1’s tube definitely has a bit more clearance, but the A6 seems like it would have trouble fitting the diameter of a thicker double-wrapped protected 18650 (I don’t have one to check with). The walls of the F1s tube seem as thick as the A6. They did do something interesting though, they have increased the inner diameter of the tube in the middle section, under the knurling. I’d guess the wall thickness is about the same throughout though; the knurled section has a larger outer diameter. I suspect this was done to reduce the weight. It might also reduce heat transfer from the head to the 18650 cell. I think it does contribute to the battery feeling like it has more play.
The microUSB cover on my F1 was very hard to loosen the first couple of times, but now it turns while still remaining securely snug.
The beam of the A6 is probably better closer up, as well as being slightly “cleaner”
I think I’ll end up using the F1 more, for two reasons. First, I like having the side switch. Second, the USB charging makes it much more self contained, which makes it more useful in many situations.
The USB port also makes this more practical as a “muggle” If I given someone an F1+a battery, they can just use it.