Big races tell you a little, but to be honest most of the guys in the A main, would be in the A main, regardless of what they were driving.
Look at what most people run at the tracks you will race most.
See what manufacturer spares your Hobby Shop carries.
Look what the fastest ( and most helpfull) person at your track runs.
Any of the cars listed are great. RDX/T2/Tamiya and you will not go wrong with any.