IMO I would go with the 73 because it is the earlier of the two produced. The further you got into the 70's the worse quality and power became on our cars. That was the reason I went with 71' roadrunner cause it was the last year before emissions and alot of good engines like the hemi and 383 disappeared. I've seen some nice 73' and 74' cars, I just could never get into the body style.

My point of view is based on if you plan on sticking with the originality of the car. If you plan on customizing it, then the 73 would be a better choice because of the hood design and they were still a fairly rigid design. To me, the 73-74 don't look a whole lot different. Same goes for the 71-72 roadrunners, the only difference really is the grill and lights.