I can totally understand why people do not like Hayate, but sometimes it can really exaggerate and go overboard. I used to not like Hayate myself and preferred Ein, but when I learnt more about Hayate, it seems that Ein is the one that has less personality than him.
IMO, I have seen Ein as more of an enthusiastic and confident fighter with coolness while Hayate is extremely snarky and a bit too arrogant for his own good, while at the same time quite honorable. (I'm probably going to get bashed for saying this)
The coolest Hayate has been was DOA3, he had very Ein like intros/outros with a ninja twist. He's been somewhat boring every game after, doesn't help he's always getting his ass kicked
He doesn't do anything major in any timeline, the most he did in story mode was kill fake Kasumi teamed up with Ayane and even then it was Ayane that actually landed the fatal blow lol
I'll ease up on Hayate riffing when he actually does something except get his ass kicked.
I still don't understand how Hayate's a stoic anime ninja in DOA4 - 5. You can literally hear the snark in his taunts and quotes, especially in his English voice. I would say that Ein has even less story than Hayate other than having amnesia and getting back his memory.