I'm the opposite in a way.
I don't like Zenos, but I feel he was a poor fit for SB. Because he didn't care about the actual struggle. He didn't really care about the revolution or garlemald, he was bored of the plot and only interested in fighting us in the latter half. I think a villain for 4.0 that actually believed in garlemald,that had an actual personal investment in the conflict would have worked much better. But I'm more open to the possibility of him maybe working better in Endwalker where he may fit the story better.
I didn't have a problem with him beating us. I don't care that there's someone stronger than us blessing of light or no, that's fine. My issue is that we just sort of 'leveled up' to be able to fight him in Ala Mhigo and that's boring. The victory didn't feel earned, nothing we did in SB felt out of the ordinary from ARR and HW, we didn't train to counter his style or fine some strategy to beat him. We just kept doing the same thing and our numbers went up so now we could fight him. That wasn't satisfying narratively.
My biggest issue with Zenos though is that there's just nothing for me to latch onto as of yet. The potentially interesting arc of him having to be smart and strategize in order to reclaim his old body was glossed over, he was never shown having any actual difficulty or struggle. And I think that's part of the issue with him. Part of the reason that say, Kefka works for me in VI is that he has to scheme and plot and betray his way to getting power. He's no more sympathetic than Zenos, has no more depth than Zenos, but seeing him work his way up to becoming powerful is more interesting than how Zenos has been handled. And while Kefka had no depth, he's amusing in a way for me with his pesronality where Zenos just feels flat and boring.
Zenos doesn't need to be sympathetic, but I need SOMETHING to latch onto. Something for him to struggle and work for that's engaging, an interesting if still selfish motivation, a more interesting personality, SOMETHING. But for me there's just nothing there and I'm as bored of him as he is of life. I really hope 6.0 changes this for me, I don't WANT to be bored of the main villain. But it doesn't help that he's not really done anything new since being brought back from the dead. He just wants to fight us again, and Fandaniel is the one with the actual plan here, the one actually pushing the plot forward while Zenos sits around on his chair and decides what beating stick he wants to fight us with next.