Here's yet another opinion, based on my own experience with both lights. I have carried a Photon and an Inova on my keychain for well over a year, so they've both been well tested for EDC purposes. There's one problem that has occurred for me, and it's come from my preferred light, the Inova.
I find the Inova easier to operate by touch than the Photon, which requires more manipulation. Press it once, it comes on nice and bright, press again, it comes on with a lower light level, then press the third time, it strobes. I own quite a few Inova's, vs. a couple of Photons, but unfortunately, it's the ease of turning on the Inova that causes a problem.
In the past year, as I've used the Inova more and more, that light has gotten broken in to the point that I frequently find it's been turned on accidentally. It's pretty obvious at night, but there have been quite a few times when I'll put my key chain down during the day, only to see the Inova mistakenly glowing brightly. It's never happened with the Photon. Obviously, we all have our keys situated differently, we have different grips, etc., so YMMV.