there are so many flaws with your reasoning in that post. first and foremost, you were comparing the abilities individually, which is never an effective way to compare to champs. and then there's the flawed reasoning within the comparisons themselves.
as for the passives and the comment about atk speed, neither one of your points there are really true. her passive actually does more damage than his, both immediately and over time. the ratio and the base are both higher, and his has a cd whereas hers doesn't. as for atk speed, not only does she have the 20% atk speed boost from her passive but she is far, FAR more aa reliant than ekko. she actually utilizes her aa's a ton, especially early game, whereas ekko's extent of aa reliance is in procing his passive.
your comparison of the q's doesn't make sense honestly. first off, about 3/4 of his q damage are on the way back, and 90% of the time getting hit by that thing a second time is just you positioning badly. the other 10% consists of him being right on top of you or you being cc'd. and even if it does hit both on the way there and back, it doesn't deal that much more damage than a Diana q. so technically, yes it's stronger. but realistically, Diana's is stronger.
ekko's w is only sort of a combination of her w and e. his is entirely for utility. while her e is for utility, I honestly cc it as a stronger form of cc than his w because her's is a displacement. as for her w, I see it as being far stronger than his w because not only does it shield her for a ton, but it also deals massive damage if you hit all 3 orbs.
his e is entirely, most definitely nowhere close to being a stronger version of her ult. sure her ult has a longer cd if you miss her q, but hitting her q isn't hard. it also deals between double and triple the damage of ekko's e while also being reset by her q and letting her not only get to nuke them again but an extra gap closer in case that ziggs w'd away. I'd also like to note that his blink attack only lasts for a couple seconds, and it isn't hard to keep away from him for that long. also, not only is the total range on her ult longer by 200 units, but since his second dash is target it isn't that hard to stop him from hitting you with it (and also lose all that damage).
how many times to I have to tell people, his ult doesn't heal him for most of his hp. realistically, you're never going to heal for more than ~40% of his hp. on top of that, he is almost never going to be able to use his ult for both a large heal and a large nuke (and lets be honest, that ult is 90% of his teamfighting damage). and lets not forget that his ult has an indicator that lets you know exactly where he's going to ult to if he would ult at any given moment.
and then, last but not least, every single one of ekko's abilities are extremely projected and very easy to work around. the only thing you should have a problem with when facing ekko is killing him since he can ult away.