Maokai is the best rework of the group

and it's not even close, in my opinion.

The % damage being put on saplings was a really smart idea. His jungle clear is fucking great now, especially once you get used to managing bushes to kill any camp besides the wolves with ease. Top lane took a hit but good riddance, he should've never left the jungle. W is now a one-point wonder, I think; the added time to bush saplings and the extra damage puts him on par with Shaco in terms of turning bushes into death traps. Ult gives him huuuge zoning power anywhere he tosses it, and thanks to it he might become the only champ to use Righteous Glory. And he actually manages to have a good amount of counterplay despite most of his kit being the same. I personally think you should still rework his W to offer some here, but that's besides the point. Saplings are visible and can be countered by vision when planted in bushes and they can be outran fairly easily post-early game; if he's counterjungling you then you can pull the saplings to the mobs and have them help you clear faster. His ult, which is now the bulk of his hard CC, is easily avoidable and requires clever use on Maokai's part to trap you, and you can prevent those situations with good vision. And he actually feels really good to play, especially with his new passive's late game healing potential MORE than making up for his loss of a traditional defensive steroid.

Zac's Q is really fun to use if not a little clumsy, but his ult just feels horribly misplaced and not as exciting as him bouncing his way through a teamfight. If his current and new ult were combined somehow I'd be a little more open to trying it.

and I've already established my feelings on Sejuani.

TL;DR Play Maokai next patch, he's great.