I have pre-ordered all three games and so I will be playing each of them. That being said, based on what I have read, seen and to some extent played, here is how I rank the titles based on level of anticipation and expected play time.
1. Forza 7 - I have been playing Forza religiously since the original Forza 1 launched in 2005 on the original Xbox. It has never disappointed me. I have been playing Forza games with a wheel and pedal set since Forza 2 and Forza 7 will continue that tradition, but the experience will reach new heights. Thanks to my Arduino adapter and GIMX software, I will be able to play Forza 7 on my PC with my Accuforce wheel, Main Performance PC Simpedals and dual Thrustmaster THR8S shifters, one in sequential mode, the other in H pattern mode. I have been playing Forza Horizon 3 and Forza 6 Apex with this set up for almost a year and it works quite nicely. Moreover, Forza 7 will be available on PC and will work with my triple screen set up just like Forza Horizon 3. I just upgraded to a GTX 1080ti GPU and so I should see 60 FPS+ even at 7680 X 1440 resolution with Ultra settings. Forza 7, like FH 3 and Forza 6 Apex will use Turn 10's Dynamic settings system, which allows the games to run very smoothly. Turn 10 has created an excellent graphics engine on Xbox and PC. Coupled with the 700 cars and excellent track selection, and a deep career mode and drop-in friendly online system, Forza 7 should be the sim racing title that gets the most play time from me starting later this month and so I am anticipating it the most by far.
2. Project CARS 2 - Steam says I have spent over 150 hours playing the original Project CARS on my PC and so that should tell you something. The key differentiator for me with Project CARS 2 is the superb VR support they are including from Day 1. GamerMuscle has already done several videos touting the excellent VR support and so I am looking forward to it very much. I will be using my Oculus Rift to play Project CARS 2. I also am certain that Project CARS 2 will be supported by Simxperience's superb Sim Commander software and so I will have full use of my four Buttkicker amps and transducers, as well as my Accuforce wheel.
3. GT Sport - I love the GT games but they definitely have lost their lustre compared to more recent sim racing titles including iRacing, Assetto Corsa, Project CARS, Forza and Raceroom Experience. I played the beta and it was good fun, but it did not look great on my center 1440p monitor, which is what I will need to play it on in order to use my Accuforce wheel, MPPC pedals, etc. Otherwise, to play it at 4K on my 40 inch 4K TV, I will need to use a controller. The game looks amazing at 4K with HDR, but I prefer the buttery smooth look of Forza on my 1440p Gsync compatible monitors. Because I can only play GT Sport on my PS4 Pro, however, I cannot take advantage of those features and will be relegated to 1080p. Looks aside, the game plays nicely, but I prefer Forza 6 Apex and the original Project CARS. My guess is that the gap between GT Sport on the one hand and Forza 7 and Project CARS 2 will be even wider. In summary, I will play GT Sport, I just don't know whether I will want to play it as much as Forza 7 and Project CARS 2.