bright = short runtime
dim = loooong runtime
very easy
;)
as You typed both of Your needs, imho there are 2 models:
1st of all: the one "best" headlamp, the Princeton Tech Apex.
Check around, there is model change atm, maybe You can get one for under 50,--
2nd: something smaller and also less "diverse", a Streamlight Argo HP f.e. Fed this one with a 17650 Li-Ion cell and be ready
(if You sometimes think it is not powerful enough, remove the old Luxeon emitter with a newer led by emitter swap)
PS: imho You need 2 lights. A headlamp with long runtime and a handheld light for more powerful output.
Because any headlamp that comes near the light of a handheld, also suffers from the runtime problem