You do know the Play 3 is discontinued…right? Also the theory as to which sounds better will come down to subjectivity of the listener.

Assuming you can do a A/B comparison there are differences in how each can be used and/or integrated with other Sonos. Doing research on both may help you decide which is more likely to fit into your specific use case.

Yes, just looking at used speakers and wanting to add to my house.  Just wanted to get best value for sound. This would be music mostly and maybe occasionally I would make them surrounds if I wanted to make a movie night a little more fun in my living room.   

Therein you have your answer…two Moves cannot be used as surrounds. So if using Sonos as surrounds is a possibility in the future you’ll still need the Play 3’s. If you want portability and Bluetooth capability as well as AirPlay2 you’ll also need the Moves