You clearly have not been playing League for very long if Ekko is the champion you hate most.
I am not saying that your opinion is wrong, but of all of the B.S Riot has pulled out on champion release, Ekko is probably around the ~3rd most balanced in a while. I am actually relieved that he isn't more OP.
Even though his ult costs no mana, his bread and butter Q and E are some of the most expensive abilities in the game. In addition, his health regeneration is terrible and he generally doesn't have access to LF or SV.
Most competent players can hold their own on their mains against an Ekko of equal skill level. Most of the outplays I seen so far with Ekko were because the enemy got greedy or didn't keep track of his ultimate indicator and got nuked.
The last time Riot tried to create a skirmishing assassin like Ekko, they made this abomination
. Despite excelling in long fights, he also had the HIGHEST AP + AD RATIO on his 3 second guaranteed dash with Sea Stone Trident and Lich Bane up. Fizz's kit had so much damage that he was infamous as the assassin who could kill without his ultimate.
Furthermore, when Rek'sai first came out, she had crazy ratios as well on her Q. In fact, Rek'Sai's Q combo would out damage Riven's. She can essentially fight 3 people at once and still come out on time since she was literally doing Riven level of burst damage to all 3 targets.
Yasuo had 1.2 AP ratio on his E which stacked up to 4 times upon his release. His level one cheese was basically landing 2 full stacked Es on the enemy and first blood was guaranteed. He also regenerated an x% of his shield per dash. At max rank of his W, his formerly 690 hit points shield is up every 4 dashes.
Almost every champion was broken upon release except for the cases of Vel'koz and Bard. Besides the exception, all of these champions pretty much took over the role they were made for for a few patches. Current Ekko stands absolutely no chance against any of these pre-nerfed champions.
Objectively speaking, Riot could have done a better job, but relatively speaking from their past performances, they did do a better job.