DayZ is a cool game, but it's been in Early Access for 7 years. Many bugs and game developers don't work much on it. 7 days to die is great
I played 7 days myself and makes mega fun with friends but I think at DayZ you have to rent a server (I heard it from a friend)
Dayz is relatively relaxed and full of cheaters. I always wonder what you do in the game when you are fully looted. The most exciting phase is the beginning when you first have to collect or craft food and weapons. Once done, it quickly becomes lame.