You need to find a review written by an enthusiast with measuring, or at least estimating equipment. Assume all the *fire brands are outright lying. Cheap stuff claiming more than about 1500 lumens per 18650 is usually lying. There is, however a pocketable, $40 flashlight that makes an honest 4000+ lumens on a single 18650: the Emisar D4. There's a catch though: it's dissipating about 80 watts of power to do that and thermal throttling kicks in after a few seconds. To give it more HN cred, it has an open source firmware.
As to your request, a couple general recommendations first: skip the zoom, and don't chase output numbers. Zoom is pretty optically inefficient, and small zoomable flashlights don't end up with much more throw distance than similar size fixed reflector flashlights. They don't do wide-angle illumination as well either. A good reflector with sufficient output provides both at once. As for brightness, human perception of brightness is roughly logarithmic (with a base between 2 and 3), so it takes four times the output to look twice as bright. Anything over about 500 in a pocketable flashlight is pretty decent, and most 18650 lights have more.
Specific recommendation: the Wowtac/Atactical (both names show up on Amazon sometimes) A2. This is one of the smallest 18650 lights, has shortcuts to low, high and last-used modes from off and has a right-angle configuration that works equally well handheld of as a headlamp. A pocket clip, headband and 18650 battery with built-in USB charging port are included. It costs $20, and I have no idea how they make a profit given all the stuff it comes with. Go with the neutral white tint if you can find it; this looks more like sunlight and won't wash out colors as much as the cool white.