Ekko is my main, I spend a larger amount of time playing him. Ive tried most builds and played with a few of my own. However this build gives me the most success in the mid lane. His early power mixed with the tears mana effect makes laning against ranged champs much easier. Play passive and poke well till lvl 3 then a good combo into his w should get you a kill. The build is rather tanky for full Ap and gives to time to play around the enemies position and abilities. The on hit of lich bane and his w passive make for good outplay potential. Also with this build using his ult offensively vs a panic button makes for more rewarding play. I put Annie as a counter for the point and click stun but playing around her passive will get the win in lane. Last thing replace with sheen with an early seekers armguard when playing yas or zed and you should be good.