I have seen this soon 2 years old thread before, but because I find it such a dilemma for a flashoholic to make the decision for only one, I have not yet answered. But I will now give it a try.
I base my choice on following criteria:
1: quality and durability
2: battery availability
3: beam character and tint
4: hold comfort
5: size
The result of these criteria then will be Fenix TK20. Likely the highest quality flashlight Fenix ever made. Superior hold comfort, very nice tint, bright spill, good throw, and usable with three different battery options as well primaries and rechargeables.