Ok, I've never tried AC but I did try pCARS on a controller and it was utter s:censored:t, it was a while ago and I remember playing the first race with clios... that FWD car spun out on the STRAIGHT!!! Then I tried M3 e30 and even if you get a hint of oversteer it is impossible to correct it, messed with the settings and controller presets for an hour, nothing helped, sold it for 2/3 of the price.(NOTE: pCARS is probbably x100 times better with a wheel but I don't have it).Got back to GT6 and it was just amazing, first I drove an NA mx5 and it was very easy to drive, well balanced, oversteery but fun, then I tried NC miata and it was a lot more planted and serious than the NA, then I drove an EK civic and it had "pronounced" exit understeer, then I drove an NSX and that thing was like a dart, then I drove a 787b and that thing was very twichy and unstable but menagable... Anyways my point is that it's incredible how good GT6 play's with the controller.(I guess you could say that's groundbreaking by itself, lol but let's not go there)
One more thing, GTS doesn't need to be groundbreaking just because it's bigger name than the rest, it just needs to be better than pCARS and AC. People won't care that GTS isn't groundbreaking as long as it's the best console sim out there.
And will it be the best? We'll just have to wait and see