it all depends.
for a beginner/novice i would choose the mtx-3. it is very dependable, it is almost as fast as the 710 or rrr. performs 96% as good as the best pro cars out there. very easy to work on.
if you are an expert and do not wreck a whole lot
i would go for the serpent 710 or kyosho rrr.
i think the hpi is not as good as any of the cars mentioned above, its a good car, just not as good as the newer cars out now.