I've played a lot of DayZ, it's really good but incredibly frustrating, you get stacked, run around and get shot on site by some dude. Zombies kinda don't exist at that point of the game either and if you see any there's only really 2-3 around, none to really cause an issue. Not only that but if you do fight them it's still really buggy especially with melee weapons.
It can be really good and has its moments, I remember one time when I was in a military base and was following two dudes that had walked in to a building, we both heard each other so there was this standoff between the 2 of us for 30 minutes. I then died because they called their boys :(
H1Z1 to me gives you those moments, they may not be as tense but they happen a lot more often which is really good. There isn't as much running for hours just to get to one side to the other. There also seems to be a lot less glitches in the game, like fuck, dayz still has zombies walking through walls/doors.