This one or the M&p 15 sport 2?

My vote is the Del-ton. It is more up-gradable as it is closer to true AR specs than the Smith. Example of Smith vs Delton : youtube.com/watch?v=ooFcQ2cyrkE

They are both great guns I have the sport II mainly because I know S&W will be around if I ever need any parts Mine is stock and will not be really modified . Now if I had the desire to tinker with and modify a AR-15 I would get the Del-ton