I own G3 and I agree most come down to G3 and Aerofly both really nice sims. Although G3 does not currently let users import there own planes it is being incorparated into the game it was suppose to come out with the latest patch from what I read but didn't fall trough. So I would say the next patch for G3 will let users import there own planes. This is a big deal to me also since I am a modeler and I can make my own planes and I am unable to do so. But G3 is offering a closed beta at the moment for users with a official 3ds Max license. So its really your decision if you want to be able to incorporate planes now and don't care about multiplayer get Aerofly. If you want to be able to do this in the future and would like to have multiplayer as a bonus get G3. I am a helipilot so I don't mess with planes to much besides when I am bored. So far as physics I would say they are both the same.

Either way you can't go wrong with any of them. Both are great for new people to the hobby, and offer alot of inexpensives crashes . If I wouldn't have had a sim I would probably have a $1,000 bill in repair parts lol