Get the car that best interests you but also take into consideration the car that best suits you. Which car does your LHS carry parts for? That is very important since if you need a replacement part you won't have to "mail-order" everything. In the long run shipping becomes very expensive.
Also, what type and size of tracks do you plan on racing on? If your local track is tight and technical, get the NTC3. The shaft driven transmission is more efficient than a 3-Belt transmission, which will give you better acceleration coming out of the corners. If you race on a larger more open track the shaft driven transmission really has nothing over a 3-Belt transmission. A shaft driven transmission is more durable though so if you race on a track where its dusty and rock-laden you would be less prone to drivetrain damage. The most important factor of all like I stated before is parts availability in your area. It stinks to not to be able to race because you are missing a screw and can't get it til' next week.
I race a Reflex NT and parts availability is very scarce where I live. I almost have to mail-order everything. With all the shipping expenses I probably could have bought another Reflex by now. Have I learned from this? No, I will be soon getting a Kyosho V-One RR. No shops in my area carries any parts for Kyosho to boot. Everyone at my tracks races NTC3s. What can I say, I like to be different.