Over the years I have built TL01's - TA05's - 416WE's - Pro 4's - Cyclone - TCX - M03 - M05 - Photon EX's.
I have just built a D06 which I have found the quality the best I have ever built as in style, very little shimming required compared to others and the kit comes with 3 mm shims all sizes no extra's really required, except for the arms and usual spares for breakages.
I have heard good things about the ARC - Team C, the thing with Xray good car but when you make a change sometimes you can not see a difference, as for the BD7 guys I know who are fanatics have said the quality is not the same one actually got tie rods in the kit with threads on only one end, and they had to buy as they said go fast bits.
It is always a hard decision but what has been said is something to think about, what is raced at the track you are racing at so if you break something and you don't have someone might have a spare to lend you and you replace it and how fast you can get spares.
Goodluck on your decision.
Noel