To reiterate what some others have said on this thread -

The "perfect" LED headlamp would be one that:

1. can handle getting wet
2. is easy to change batteries
3. has two brightness settings (not overly complicated)
4. uses AAA batteries (same as other gear requiring batteries)
5. can be tilted to point at what I want to see (not just flat against my head)

I currently use a Petzl Tika (or tikka??) and really like it. That said, I only use 2 of the 4 settings on it, and the design is such that it is a little bit difficult to change batteries. I also wonder what would happen if it really got wet. Luckily I haven't found out yet!