18650 is like AA over dosing on steroid. It pack a lot more energy in a slightly larger package. This extra energy from 18650 allow for more ampacity deliver from the battery. Most 18650 can deliver 1.5 amp at 3.7 volt with ease. Better manufactor like the Panasonic cell easily handle over 2 amp load with less internal resistant than typical AA. That being said, the power from 18650 cell can allow flashlight manufactor to develope flashlight that is capable of producing 700+ lumens. Not only will you get more punch out of 18650 flashlight, but the battery is also rechargeable for many cycle. You will easily find fox and deer at a distant with most high power 18650 flashlight.
The downside of 18650 cell is that it is not for everyone. The disadvantage is that 18650 cell cannot be mishandle like AA cell. You need to take some care and precaution with 18650 cell. For a starter, never charge these cell unattended at home. Do not abuse them like dropping them or crushing the cell. The battery can causes fire when these warning are ignore. These incident are few and rare but it does happen. Personally, I myself own many 18650 cell and charged them countless time without ever having one issue. Stick with buying quality cell like AW, Redilast, Callie and you will be fine. Many cheaper brand like *.fire is OK and most likely safe but does not perform as good.
If you do venture into the world of 18650, you will find many flashlight that are rated over 200 lumens. Most peform at least 500 OTF when using the XML led. Being a newbie to 18650, you should stick to single cell 18650 flashlight. Do as much research with double 18650 cell flashlight before going that route. Shiningbeam has many flashlight using 18650 cell that are very good. Many are under the $50 price range, but that does not include the battery and charger. They also offer AA flashlight if you decide to stick with that route.
It is hard to go back to the AA route once you step up to the 18650 flashlight path. The first thing you will say is "wow" this light is very bright when you turn on a light utilizing 18650 cell. For some of us, it becomes a flashlight hobby after crossing that 18650 path.......(I'm one of those who had that 18650 flashlight addiction)