I would have to second the TLS head. Mine is an early model two-cell single output version. I will most likely get the newer low/high output version.
I prefer it over the Surefire TIR optics. The Surefire's TIR optic you see in the KL1 and KX series produce more of a concentrated narrow beam with some spill. Very good for distance outdoors. They are good candidates for a beam diffuser. The TLS has a very discernable hotspot but much more spill. I find it much more useful indoor and out.
MSRP for the TLS is around $75 and around $109 for the KX2.
I also recommend the Malkoff VME head if you prefer a single stage head. You can use any Malkoff LED dropin. The high powered M60, flood versions, low output versions, etc. When new brighter dropins become available you will be able to upgrade the head. A VME head and a Malkoff LED of your choice package will run about $85.