Hey guys im Doomtide im from The Netherlands so sorry for my bad english if you see grammer mistakes :3. I play on EUW Servers and this is my first guide ever.

In my opinion you dont do your damage fast enough with Ekko. With his awesome passive you do insane damage because it scales on AP and you have to get 3 stacks for it to do damage. So attack speed + AP makes him an absolute god! You can use this build top to if you prefer

Pros

Awesome passive
Good farm because of his Q
Much CC
Amazing escape/juke abillities

Cons

Mana problems early game
Some abbilities are hard to land
Ends up squishy late game

Z-Drive Resonance

This my friend, is the reason why i go attack speed Ekko.
When you attack a champion/minion/monster with your basic attack you gain stacks.
At 3 stacks you do damage for 15 + (12 x Ekko's level)+ 70 % of your AP. Thats a lot of mathematics and damage! On top of that you slow your target and if your target is a champion you gain additional speed. You can basically just dash in with your E do insane an amount of damage and just run back as fast as you can. Crazy right?

Timewinder

Timewinder is an awesome skill. It slows, It does much damage, It stacks up your passive,
it can help you escape and i always use it for farming or pushing. And that are enough reasons to max this first.

Parallel Convergence

I always take this ability on level 2 because it really help last hitting because of the passive Parallel Convergence has.
This ability can be hard to land so you can use your E To help yourself getting the stun off on them.

Phase Dive

This ability is like all other Ekko abilities. Awesome. You can use Phase dive to jump over most walls in Summoner's Rift. You can use it as escape when you are in danger, as an gap closer or you can just use it to do damage.

Chronobreak

Chronobreak is Ekko's Ultimate. When you get your ultimate Ekko will be followed by a time-delayed hologram that tracks where he was 4 seconds ago.
When you activate Chronobreak, Ekko blinks to where the hologram is at that moment and does magic damage too all surrounding enemies and gets healed.
You can use this for doing damage, For healing yourself, For getting out of a dangerous situation or for stealing Dragon or baron

Your job in teamfights is to drop your W at a place where there are many Enemy champions. Dash in and KILL EVERYBODY. Simple as that

Thank you for reading my guide. I hope this helped you.