I started with the GTS4 as it seemed the best for under 10k but in the end I found the Sunny was basically the same but lighter, despite the Skyline's street cred.
I am probably the only member of the GT2 Sunny Fan Club.
Probably the easiest car to drive in the whole game, and you get a 9500rpm redline. Nothing special, but fun for beating the SuperTouring series and Luxury sedans.