I know, I know - we're all secret console/mobile lovers and we're not "missing out" on anything - but the public persona of many people here is "I'll die before I play a console or mobile game" and so we should fill them in on what's missing from their lives :)
For me, the PC would be a better thing with Forza Motorsport.
It's not quite the sim PC owners would like but Forza3/4 offered some of the best 'pure racing' entertainment I think I've ever had. The AI actually plays along, there's no obvious 'rubberbanding' (and the replay system gets you out of that anyway) and the game can be genuinely challenging (I'd argue that on the highest settings, it's VERY hard to beat, in fact).
Forza Horizon is rather different, but after playing a tonne of it today I'd easily recommend it too. It has a nice balance of stuff, the challenge is there (and can be dialled up/down as you see fit) - hell they even resisted the temptation to pack the game with traffic (games like Midnight Club 4, Burnout Paradise and NFS:MW get 90% of their challenge from expecting you to 'race' in actual traffic!!)).
So that's my donation to this - Forza - PC owners are missing out on it.
What else (let's see how long we can do this without someone mentioning Halo eh?) :)