My first tac scope was an XTR2. It was an early model with 8 mil turrets. I dropped it after slipping on some ice and it wouldn't hold zero. When I sent it in I asked them if they could do something about the poor IQ. When it came back I was shooting with a buddy who had an Razor g2. We were shooting through some nasty mirage. I could make out the targets a lot better than he could. He looked through my scope and got pissed and sent his RG2 back to Vortex. They said it was within spec. (I am a Vortex fanboy and currently run an AMG for just about everything).
I also bought a 5-30xtr3 as a backup scope and my wife ended up adopting it. I have had it next to my AMG several times. It is very close. The AMG has better resolution, but the XTR3 has better contrast. If the image is contrasty I can see more with the AMG. If everything is the same damn color I can see more with the XTR3 because of the contrast. They are that close.
I have not compared my xtr3 to much but I have compared the AMG to a 5-25 ATACR, G2 Razor, K624i, Bushnell DMR2, and a TT 5-25 lol. Obviously the TT blew it away. The Bushnell, surprisingly, wasn't terrible and K624i wasn't bad either. The rest were annoyingly worse in the image department. Given how close the AMG is to the XTR3, I'm betting the XTR3 holds it's own in comparison to other $2k optics.