It depends on what you want to do with it and if you race what class do you want to run.

If your wanting to run 10.5, 13.5, 0r 17.5 classes then a sensored system will work with those types of motors better. If your looking to run mod only then the Sensorless systems will work just as good and are cheaper. I only run mod classes so for me the Castle Sidewinder senorless system is cheap and works great plus when Castle has updates you can just download them to your speed control free of charge.

The Hobbywing would be a nice choice for a sensored system and is more adjustable than alot of other sensored setups that are out.