For all that I've played Ekko jungle, this is the best build that I have found. Late game this build stomps, as long as the enemy isn't terribly fed.

Pros
Very strong late game
Wins against most other Ekko jungle builds
Lots of survivability late
Slippery, use this to counter jungle

Cons
Has to back after first clear
Squishy during the start game
Not much dueling potential early

For the first clear you want to start gromp, then move to blue. After blue you can either do wolves or red buff. Either way you will still have to back after. Ekko ganks are challenging but effective, so try to snowball you're biggest asset in lane.

Overall, Ekko is one of the strongest late game junglers. If you can land your w reliably you should be able to get one or more lanes snowballed. Against strong early game junglers like Lee Sin you want to be careful, unless you can catch them doing one of their camps on low health you won't be able to 1v1.

Ekko is strong with anyone with cc. If you can get a cc chain going for long enough for you to hit your w, you can win any team fight. One thing to be careful of is when Ekko ults. If your team isn't coordinated enough, it could lose you a team fight. Let them know if you're going in or ping if you're using ultimate to get out.

The only unique skill that really takes skill to master is his w. Although its unreliable, if you get good at it and can land it almost every time you can be able to stun or slow most of the enemy team at the same time.