I could go on and on about the inferiority of AA batteries. But, alas, there are some people that insist the Ford Mustang is better than the Ferrari 458 Italia and similarly people stick by AA batteries. If you are one of those folks you have plenty of options in the Fenix, 4sevens, JetBeam world of the lights, but sparingly few in the upper echelon of flashlights. Custom makers prefer the best of the best, either high maH batteries like CR123a or CR2, or even more specialized, a rechargeable cell, like the 18650. Simply put, AA batteries do not offer the performance that attracts the attention of custom makers. That said, if you scour the web you will find a small handful of lights that use only AA batteries, offer decent performance (given the power source), and still have the fit, finish, and unique look of a custom light. Here are some of the choices out there:
Steve Ku Volere AA: Probably the nicest AA light in the world. Here is the product announcement page. Here is a good review with some sweet pictures. The form factor is awfully nice, as are the custom touches, like the preinstalled optional tritium locator on the clicky. The all Ti construction also screams custom. They are, of course, all sold out. You have to scan the forums for one being sold. That said, they rarely, if ever come up for sale. It has pretty much every feature you could want from a flashlight and still has an AA body. Here is the Ti beauty:
DST TLR Titanium: This is also a custom AA light, sold mainly through CPF. Here is the original thread. Here is a review. The high is a really impressive 220 lumens and like the Volere, the clip is preinstalled. The form factor, again, is nice considering the power source. It is not as refined as the Volere, lacking the scalloped bezel and the tritium insert, but it is still a very, very nice custom light. The price is quite reasonable too, or it was when the light was released, $139. Again, this a matter of scouring the boards for a used version.
Xeno Cube E11 V7: This light has been around for a while. It is not a custom light, but a high end production light from a Chinese company. Here is the product page. Here is a review of a slightly older version of the light. The light sells for around $80. Here is a good street price (love Blade HQ, BTW, great selection, real time inventory, and fast shipping). The light has a heavily tweaked XP-G emitter and hits an impressive 220 lumens on high. The square body offers a break from the horde of round, knurled tubes. Finally, it comes with a nice looking leather sheath. I am not a fan of sheathes, especially when you can get a light with a pocket clip, but this one is not a chintzy looking sheath.
Surefire E2L AA Outdoorsman: For years people clamored for an AA light from Surefire. For many of the reasons I detest AA batteries they resisted. Last year, finally, they caved in and made the EL2 AA. Here is the product page. Here is a video overview. It has a high of 80 lumens (noting, of course, that Surefire's 80 lumens seem a lot like a no name brand's 150 lumens). It also has that world renowned Surefire feel and quality. Still it is a big light and even at 80 "Surefire" lumens it is not the brightest thing in the world.
Photon Fanatic Ti AA: A true custom, one of a kind light from Fred Pilson, aka Photon Fanatic. Here is the product page. There are no reviews because there is only one of these lights. Fred's stuff is aesthetically beyond any other maker's lights. McGizmo and Cool Fall make great lights, bleeding edge designs, but no one comes closer to make a flashlight a work of art than Fred. I linked to this to show you what is possible in terms of a bespoke, true custom light. While your on his site take a look at the Indian Princess. What a jaw dropper.
Arc Mania Maxlite III: The myth and rumor, a light of tantalizing performance from a well know custom maker. This is line of high performance AA lights, all called Maxlite. the most recent version is the Maxlite III. ArcMania had a fight with folks over at CPF and so find refuge on an even more obscure forum, Custom Light Forum. The design of the Maxlite Extreme is really quite amazing. The body itself is a masterpiece of utilitarian design, with a built in cigar hold finger ring. The bezel is scalloped and the body, in my mind, comes pretty close to the perfect shape for a flashlight. Take a peak (it is the middle light, between a McGizmo Lunasol 27 on the top and a Cool Fall Spy 005 on the bottom):
There were no more than 35 made according to the original sales thread. They were $250 at the time and their exquisite form factor and high performance, custom electronics means they are very, very rarely on the B/S/T boards. Arc Mania may or may not be working on an update and that light, according to rumor, may hit 450 lumens with an AA rechargeable cell (using a three emitter array like on the Mac TriEDC). Again, at this point it is just rumor. But if you can find an original there are tons of mods out there for this classic.
Tranquility Base Key-Lux AA: Another super limited run custom. Here is an image:
Made by Tranquility Base over on CPF, this is, like the Maxlite, is a light that has come and gone. If you can find them they are on B/S/T boards and they are likely to have an out of date emitter. That said, these classic bodies allow for mods and many people do that work. Here is a review of the Key-Lux AA. Note that the AA head works on a N-battery body as well.
The pickin's are slim in the high end AA flashlight market niche. Only the Xeno Cube and Surefire are still readily available. But if you can, it may be worth tracking down some of these incredibly obscure lights. Their design and form factor blow away just about everything else out today and someone can surely upgrade the emitter for you.