Take a look at the Viper systems. I am running their VTX10R. This ESC will handle motors down to 4.5 turns which would be crazy fast. I'd say look at motors around 7 - 10 turn if you're wanting power/speed. If you're looking to race, then your motor selection would depend on what class you want to race.
If you are wanting a smoother power delivery definately go with a sensored system. Some sensored systems also allow for motor over temp protection (Viper does).
Viper has a great warranty and thier customer service seems top notch. They have a couple guys that help out folks on the fourm all the time.