HIDblue
Enlightened
Haven't tried the 18650 yet (yeah, I'm that lazy), but I prefer the small factor of the 123 version. One of these days. :devil:
If you're looking for a "small factor" 123 light, check out Lumapower's latest offering:
http://www.cpfmarketplace.com/mp/showthread.php?t=222823
Pocket EDC Lumapower IncenDio spitting out 370 lumens using one RCR123a or 16340. It looks like it's about the same size as a Fenix PD20, but has a forward clickie.