Ekko can easily proc Electrocute with [Q] and [E], allowing him to burst down his opponent before they know what hit him.
WhySudden Impact
After casting [E] Ekko gains both Magic Penetration and Lethality making his assassination potential incredibly high.
WhyEyeball Collection
Eyeball Collection's ability to assist you in snowballing an early kill is great for solo queue.
WhyRavenous Hunter
Like LeBlanc, Ekko massively benefits from Spell Vamp on his passive damage allowing him to sustain in lane and pressure his opponent.
If you'd prefer to have Zhonya's/Protobelt up more often Ingenious Hunter is a good option here as well.
WhyPerfect Timing
Zhonya's pairs extremely well with Ekko's ability kit as it allows him to buy time for the perfect Ultimate or [W] stun to get out of a sticky situation.
WhyCosmic Insight
Cosmic Insight's extra CDR is fantastic for early game skirmishes where an extra ability cast can be the difference between life and death.