Just for the record, this is also what Microsoft writes about Forza 7 on their own XBox store:
Experience the thrill of motorsport at the limit with the most comprehensive, beautiful and authentic racing game ever made.
reference:
http://www.xbox.com/en-US/games/forza-7
Most comprehensive? Purely on garage car count sure, even on licensing real life motorsports I'll give them the benefit of the doubt. But it has half the tracks of PCARS2, no full dynamic time of day and weather on ALL tracks. In the tech department they also run behind with no tripple monitor support, no VR, no UDP, no full controller customization, nothing to compare to livetrack 3.0, a very simplistic handling model, no FOV or seat adjustments, .... the list goes on and on.
Most beautiful? Again, can be debatable. Sure that Nurburgring demo looked great for many, I personally found that sky a bit overdramatic and the cars didn't make any trails in the wet track either (also very visible in the E3 demo). On the other side, PCARS 2 has full day to night transition which is something FM7 doesn't have, tracks really come to life in PCARS2 and that is something that is huge as well when debating which game is most beautiful. Again, they can even have the benefit of the doubt here.
But most authentic??? With GT3, GT2, GTE, Super GT and Super Trofeo all grouped together under the same banner of "modern GT", with a PI system that is completely fictional, without any practice or qualifying races, with a rewind button and an astronaut suite? Yeah right...