to the OP, go with the GT-R!! You will like it a lot. I do not really know the GT-R prices but if you get one for 60K you cannot loose much money on it. I do not know if the GT-R is really that good for DD. I was trying to get my son in the rear seat and only could do it if the front was almost all the way forward.
Still as someone pointed out the GT3 has no back seat at all. I would definately not DD the GT3 RS. Very low, loud (tire noise), very flushy etc. not a DD car. The M3 is way better option for DD. On the track, I do not know too much about the GT-R. Never driven one, I was only a passenger for about 5 laps that's it. The M3 is easier at first than the GT3 on the track. Actually the M3 is very nice on the track with R-comp tires and some brake upgrade. The GT3 RS is more fussy, more difficult to drive. I still have a high heart rate at every new session in the RS. But I am not a real race car driver, not even a true expert I think.
Anyway, you cannot go wrong with the GT-R or the GT3 either!