Buy this one
After losing my previous XP, I went through a couple of other headlamps that I picked up cheap on SAC. Even though I still have those, I went back to the TacTikka XP this year. It's just a great headlamp - very comfortable, bright, long battery life, and I really like the colored light diffusers that are included. I leave the red one in and use it for late night reading when someone else in the tent is trying to sleep.
On this lamp, the top strap is kind of useless (not to mention dorky), so I broke mine off. Still works like a champ.