I have a Powerspec, DaVinci XYZ 1.1 and Airwolf 5.5. The Powerspec blows the other two away. Using a two headed printer can be a pain because even when leveled the second head often knocks the print off the bed. I ended up taking one of the nozzles off my Powerspec and use it as a single headed printer. It is much faster than the XYZ and much better detail than the Airwolf. I haven't actually turned on the other two printers in months.

Buy the Powerspec, print in ABS. Fantastic deal.