Battery compartment on the rear is much more comfortable.
However, the Lightwave Illuminator is a good one, even though the batts are in the front. It uses 3 AAs and can use Lithium AAs. It has 4 white Nichia LEDs, with an easy twist on/off.
If you have a Petzl Zoom series, you can get 3 white LED bulbs from C. Crane
www.ccrane.com and they have them for 4.5 and 6 volt Petzls.
If you have a 3 volt (2AA for instance) incandescant, that is PR based for the bulb, you can get the Versalux PR-2 from
www.techass.com (alkys only for this bulb).
So, there are alot of options available.
I have a Zoom Adapter and Zoom Mega Belt with LED bulbs installed (these are custom 9200 MCD single LED bulbs), PT Solo w/Matrix Module (regulated, but not really bright), Coleman Peak 1 Expedition Headlamp (2D) with a Versalux PR-2 (really bright), and an Illuminator, which is the only 'made as' and LED headlamp I've got.
What you get, depends on your backpacking philosophy, time, and expedition type.