Rfactor doesn't really deserve to be there, because it's just F1 challenge with a few extra features added.
GTR deserves it because it has a few smaller details that othjers miss out, such as very grip on different parts of the track, and night and rain racing, something ehich a remarkable number of Sims don't have *cough cough*.
As for iRacing, it seems to be based on N2003, which is a good thing, (I love the way they've just nicked a lot of the sounds straight fom N2003
), but its all done delibreately to shut the every day person out methinks, its more about the rich/ serious.
If they didn't have the stupid rental idea, I might even buy.