I got my hand on Arena Commander, sure it's shiny, it's magnificent. But, I got no feeling on dogfights. Ok, that is an alpha. But, hell, Chris Roberts has delayed the Dogfight Modules several times. And I'm suspecting the release of the Alpha of Elite: Dangerous, made Chris to delay the DFM. Elite Dangerous is totally gorgeous in all way. The feeling to really pilot a ship, the sense of speed, the power of our guns, all of that make the dogfight very appealing.
It's not the case on Arena Commander. And, and the physics behavior is weird on Arena Commander with my Hotas X52. It's pretty hard to pinpoint my lasers to my target. The ships move pretty slowly. I don't have any feedback when I use afterburner. The same goes to when I got hit on my shield.
So, for now, if I have to recommand a space sim as it is, I recommend strongly Elite: Dangerous.