This way to the Z.A.C, little dude
I've been a zac main for a really long time, and I really wanted to weigh in on the zac changes.
Before I do, I want to say that I do understand where riot was coming from with this rework, and I'll strive to be as fair as I can be. but without further ado...
lets start with the E changes. I think I get why riot reduces the stun timer; zac shouldn't be able to guarantee that any target he lands on with his e will be guaranteed to get hit by a fully charged ult. That'd just be too broken. Still, it severely impacted his dueling potential, and I think that needs to be addressed. Zac's most critical strength in 1v1's, or at least close 1v1's, was his ability to throw down all of his spells at once and use the stun from E to run and get some blobs. That's really just not practical anymore; you have to commit to either killing them in one go or stalling for time, not both. If that was intended then fine, but I think it's worth considering.
I don't really want to weigh in on the ult. I can tell it's high skill; a zac should re-assess where he should aim his ult with every passing milisecond. If only the tanks are left in it you should drop them away from the fight, if the carries are the only ones you got you should deliver them to your team. Much like a bard ult, you need to consider the effect of every champion caught in it and that's cool. Because of this skill ceiling, I feel a little nervous about every observation that I'm making here; if the ult can be perfected, it could make zac an enormous high-elo balance problem. I don't really want to comment on how it could be changed, but riot should keep an open mind to ways that this spell could be more synnergystic with the rest of zac's kit.
Zac's new q is bad and needs to be buffed. I get what you guys were thinking; it's like a blitz hook, which makes blitzcrank good even though it's his only spell. But it's not like a blitzcrank hook. A lot of the time, landing the q and autoattacking something just isn't plausable. If there aren't any minions nearby you can't AA, but if there are too many minions you can't land the skillshot. What's worse, because having to deal with the dynamics of two constantly moving objects is really really hard, you never really know where the targets are going to go when you proc it on two champions, which is a minor complaint, but I really felt like I should have been more rewarded when I managed to hit two champs at once. It's not usually an easy thing to do, especially when you take target selection into account. I would strongly consider upping the damage potential of this ability, giving zac a second q cast instead of an auto, or something else drastic. This ability alone makes me not want to play zac.