Well if you get an MC-E, I wouldn't recommend the TrustFire one or the unbranded (=TrustFire) one. It didn't work when it arrived, it had a horrible lens, the beam pattern is yucky IMHO, and it was glitchy until I did some open-tailcap surgery. On the bright side (haha) it has about a 1:25 runtime, so it can actually be used for the homebound leg of my commute if I keep my pace up.

For perspective on the beam pattern, animated GIF.