It's no secret that the top lane tanks ate it pretty hard in patch 7.4. Maokai took the nerf bat right to the shins, and it wasn't the nice padded kind either. Nautilus, Poppy, and Shen were all unaffected by direct nerfs, but all three of them ate huge damage nerfs via the offensive mastery nerfs that have already caused their win rates to drop. While the biggest boogeyman of the top lane, Quinn, is now no longer an issue, there's still quite a number of carry top laners to compete against, include the still potent Darius, and things are looking grim for the tanks.
Enter an unlikely hero: Zac. Zaun' most prized amorphous being may soon be crowned the king of top lane once again, as he has a unique set of properties that make him a strong pick. First off, he's a flex pick. Zac is mostly known as a jungle champion, and picking him early on in the draft with the intent to send him top lane means that the enemy team will likely anticipate that he'll be in the jungle, giving both you and your own jungler a potential in the draft phase. Secondly, his percentage damage and strong sustain makes his matchups against other tanks a breeze. If you didn't play during the days of Zac top lane a few years ago know that you never want to be the Nautilus on the other side of the lane from a Zac. He'll trade and trade and his lack of mana combined with the incredible sustain his blobs offer him ensures that he'll always come out ahead. Finally, Elastic Slingshot is simply one of the most powerful initation tools in the game. While it might not be the most consistent or have the largest AoE, it does have the ability to initiate a fight from offscreen -- a trait that's really only shared by Enchanted Crystal Arrow.
If you like being a lane bully, and you like throwing yourself bodily into the enemy team, give Zac a shot. He's one of the most fun champions in the League if only for the joy of hitting an unsuspecting ADC with Elastic Slingshot from offscreen while you have Orianna's Ball on you. Just remember o pack Windspeaker's Blessing and to pick up your blobs! On one's scared of a tiny pile of goo, so make sure you keep it together by getting every blob you can get your hands on!