Kled Best Build Predictions
My prediction is:

Kled is actually incredibly tanky due to his passive and the only way to limit his insane durability, especially later in the game, is stunning him with crowd control so that he can't build back Courage for Skaarl. Therefore, building Mercury Treads helps Kled not be disabled and so easily killed through crowd control.
There are four stats that Kled wants primarily: Attack Damage (he has insane AD scaling), Health (dramatically increases his durability through his Passive), Attack Speed (helps him build Courage when unmounted. Note that CDR indirectly increases his overall AS through W), and Cool Down Reduction (he has decent cool downs so building CDR benefits him a ton). He also benefits from Movement Speed and Armor Penetration. Anyways, Titanic Hydra makes his W passive deal even more damage and can either increase the damage of the 4th attack with the active or make him have 5 quick attacks by using the active after the 4th hit.
Black Cleaver gives a little bit of health, which is nice, but the main reason you get this is because of the huge amount of AD and CDR it provides. Also, the armor penetration it provides synergizes well with Titanic Hydra's passive since it allows Kled to AoE Armor Pen the enemy team, especially during his W. The bonus movement speed provided by the Passive also helps Kled stay in range after using Bear Trap On a Rope.
Ultimately, Youmuu's Ghostblade is the ultimate AD stat stick. It provides everything any AD wants offensively and Kled is no exception. Not only this, but the active also helps with escaping due to the movement speed given. Simple as that.
You know how Kled is really hard to kill because of his Passive popping back up? Well, how about making Skaarl hard to remove in the first place? By the time Kled builds this, Skaarl easily has at least 1800 HP from this and the other items you build on him. The 30% max health shield, along with the base AD increase, is just very much welcomed by Kled to make him that much harder to kill.
Death's Dance provides a ton of AD, but also finally gives Kled that sustain he wants so much. The 15% Damage Reduction also adds to his tankiness and makes him even harder to kill. Finally, the 10% CDR provided tops us off at 40% CDR, making him have the following cool downs:
Bear Trap on a Rope: 4.2 seconds
Pocket Pistol: 12 second ammo recharge, 1.8 seconds
Violent Tendencies: 4.8 seconds
Jousting: 6 seconds
CHAAAAAAARGE!!!: 72 seconds
What build are you going to try on him when he comes out?