I like my zebralight H51.
Put the holder on the back of a baseball cap, and wear it backwards. works great.
But I recently purchased an olite i3s eos.
Olite lists the specs with AAA alkaline batery, 750mah.
1hr at 80lumens, 10h at 20 lumens, 120 at 0.5 lumens.
But with an energizer AAA lithium, its 1200mah, the performance should be more like
1.6 hrs at 80, 16 at 20, and 192 at 0.5.
20 is enough for most night hiking. At 0.7 oz for battery and light its pretty hard to beat. With one extra 0.3 oz battery, for atotal wt of 1 oz, you get 32 hrs of hiking light.
The Fenix LD01 doesnt come close to the middle level burn time (3.5 hrs @28 lumens with an eneloop ~1000 mah would be ~4.2 hrs or so with 1200mah energizer.)