Zac shoud not be reverted. Here is why...
I'm a Zac main since season 3, currently diamond 1 and the old version of Zac was NOT better. Here is why:
-His old Q barely managed to do dmg and didn't even slow that much and had unreasonably long cool down.
-You could do some nice things with Zac's old version of his ultimate, like flash behind an enemy and knock him into your team, but there was only one problem - YOU WERE JUMPING FOR 4 SECONDS, UNABLE TO DO ANYTHING DURING THAT TIME, EXCEPT SPAMMING "W" (it was fun though). So it was very situational. On top of that you can do the same thing with Zac's new version of his ultimate, but now you are able to do more than just pressing "W" after casting ult .
The current version of Zac is BETTER than the old one. Here is why:
-You can create so much more pressure on the bottom side of the map after lvl 6 because of the easy double kill, if the enemies have no flashes. You can even dive if you know that the enemy jungler is not near to stop you.
-Now i want you to compare the efficiency of the new "Q" compared to the old one. With the new one you can stun 2 targets together, knock them up and slow them and have an easy E after that. As I said, with the old one you could barely slow them and the range was so short as well.
-With his current ult you can do MASSIVE comebacks. Let's say that u are losing early, but you scale better than the enemy team. And you have Zac. If he manages to land a 3-5 man ult, that's it. In high elo the game would already be over. I don't remember being able to do the same thing with the old one.
AND I KNOW. The old Zac ult was so much more fking fun, but I would rather to keep this one. It creates so much more options for good team comps, because you can bring multiple people in place. With the old one you just caused chaos the whole team fight, sometimes even trolling your own team mates.