Stuff like F1 2015, DiRT4, WRC5, Sebastian Loeb Evo and pCARS are all going to be multi platform. Pretty much the only exclusives are Forza and Horizon versus GT and Driveclub.
I was fully multi platform last gen, and played GT5p, GT5, GT6 and Forza 3, 4 and Horion. Unfortunately a choice had to be made this time round, since there's still no sign of a wheel which can support both sides.
Personally I decided to pick Sony this generation because I prefer the GT experience to the Forza experience (Key reasons being track selection, lighting model, physics compromises and reuse of the T500), at least until true multi platform wheels arrive. My T500 has been in use for GT5 and GT6 and will move over to the PS4 when I find a reason to get one. In the meantime I decided to also update my PC rig and went with the T300 rather than the TX because it simply felt like the better option (1080 degrees rotation and a better rim). No regrets on that, my PC sims are great with the T300.