Difficult to answer that one, however the 350 is more fun, but after a hard 2 hour open pit with the 350 you are knackered as the GTR is more refined and trick, and with the paddles and twin clutch, gear changes are extremely rapid and precise which probably just gives it the edge on lap times around Knockhill but only by a few hundreds of a second.
However, the 350 is in the shop at the moment with the diff, gearbox, and all four suspension corners dropped so I expect the 350 may edge it next week.