My most used and carried light is one of McGizmo's Aleph 2 babies
, with a NG700/TWOJ light engine and standard tailcap with a tritium insert. I do have a special fondness for this light. I'm tempted to send a UWOK emitter I have to Don to be built into one of his PDs, but then my Aleph 2 would be out of work, and I hate that idea! I've really enjoyed building light engines, trying out different Luxeon emitters, swapping heads, tailcaps and bodies around in the Aleph series to find my ideal light - and being able to mix and match the parts to come up with the best light for a new situation or application.
Then there is that Surefire U2. It sees lots of use around the house. And not to forget that Mag85 I've spent many hours experimenting with and optimizing. I think its about perfect now, and the raccoons that party on top of my roof at night absolutely hate it.