Up until recently, I'd have said the Olight S1A; better mode spacing than the S1 (with an extra level in the middle) and the ability to drop back to an AA, which we usually have more to hand than a CR123.
I say "recently", as it was really bought for the missus to carry for her races; the longer they get, the earlier they start before dawn, and she really needs a little light with her. She used it for the first time this weekend, and I get the distinct feeling I'm not going to see it again. 🙂
I wish On the Road did something equivalent to the S1A, but the 5C flashlight-only price of the M3 may proive too much to resist...