Okay I love the question! Still, I sort of disconnected from the main games when the 8th gen launched, so I don't think I know every design
But!!! From what I've seen, I still prefer Alola's! I just love how much sense they make! Like... Exeggutor and Vulpix change to accommodate for the different climates, Ratata adapts to the large cities and becomes nocturnal, and Marowak just incorporates aspects of their previous story with a cultural spin! Though I will admit, Im partly biased :3
I do have Hisui at second place, mostly cause of how cool it is to see these ancient versions of known pokemon! I'm a big fan of these "Okay but what was it before?" type of forms, asking what they were like on these early times with a different culture, though I kinda feel like the paradox pokemon are kinda the same concept, just not as explored as it could have been (I hate the future ones specially, just... why are they all robots)
Plus, in some of the later gens it feels less like "Okay how about we breathe new life to old pokemon" and more like "Okay we have to keep this gimmick going" (because corporation), with Legends Arceus feeling like a bit of an exception, with some genuinely creative ideas
Also, hugging you tons and tons, always nice to see u <3

