Pedal Mechanism (Yamaha has the best IMO)
Bowl Shape: Cambered (slightly squared off) preferred, better response and more focused sound. The other option is more sphere-like, this has more overtones and less focused pitch. I don't believe Ludwig offers this, Yamaha and Adams have this on their top end drums. Yamaha's carry a more cambered shape in to the lower tiers than other brands.
If money were no issue, barring Dresden Style drums you see in the large profession orchestras, I would go with the Yamaha 8300 series. (Top of the range). I would be very happy with the Yamaha 6300 line (labeled intermediate). There is also the "Pro" 7300 between the two.