I do believe that Ekko is in a very strong position right now.
Albiet he was originally designed as an AP Mage (which of course is very strong right now), the part that shines the most for him is Offtank Ekko. You've stopped seeing him go mid as much and now dominate the top and jungle.
All of his abilities cover a large array of mechanics, making him versatile for every situation. Furthermore, he has both very high scalings and above average base damage. If you added all of his AP Scalings for damage, it would be 300%, plus the 2.2% per 100 AP of target's missing HP. If you added all of his Base Scalings for damage, it would be a total of 1140 damage, plus the 5% of target's missing HP.
His passive is a 60% slow for 3 seconds, and a movement speed boost of 80% for 3 seconds. And what's the cooldown? 3 seconds. On every individual target. Theoretically, he can apply the passive effects forever, giving him insane slows and movement speed. This just makes it impossible to get him of you, as he will be fast and you will be slow indefinitely, given the situation.
His shield, in my opinion, is very overpowered, even if it has a 3 second windup. First of all, enemies can only see the zone in the last 1-1.5 seconds of the windup. It stuns all enemies when Ekko enters, slows while he is not, and gives him an enormous shield once he does. This ability is the paragon of the perfect engagement ability. You stun anyone inside it, and no one outside it will do little damage to you as you have a shield that is nearly half your healthbar.
His Q and E have recently been given buffs by reducing their cooldowns because Riot believed he was in a poor position (what?). This is not the case. A little back, they reduced the mana cost of his Q, making it very spammy. This is a problem, because it slows on contact, allowing the Ekko player to land both hits with ease with proper positioning. It would be even easier if Ekko was in front of the target with his E. It also has a delay before returning, which I believe is actually beneficial to him. It allows for him to zone with this ability, as someone who would walk into the zone would suddenly be hit twice, as the delay is not too long for someone to walk fully across.
His E has the range of a double hop on Fizz's E. It's a dash. and then a blink. It's great for engaging with his W. It's great for catching up to a target. It's great for jumping over walls and hitting someone quickly. It's great for running away. Fortunately, I don't have a problem with any of this. The problem is that the cooldown was reduced greatly, and now is too short. Combined with his 80% movement speed buff, good luck trying to run away/catchup.
There's really no problem with his ultimate, except for that it has too much base damage and too short of a cooldown. The base damage should be reduced and the scaling kept the same to promote a more AP Ekko build, as the base damage with Tankko is too high.
Overall. his kit covers almost all kinds of weaknesses. I guess his only weakness would be that he is melee. But then he can just jump on you with E, combo you, and do whatever he wants with his 80% movement speed buff while you are slowed for 60%.
His popular Tankko build abuses all of these features by making him unkillable along with his already slippery playstyle. Tankko's core item, Iceborn Gauntlet, gives him 20% cooldown reduction. With his short cooldowns, this combination is too strong.
