The Alola league, like much of SM, for better or worse, stuck to the theme of being different and really it's own thing and style
If SM's style was for you, you'd likely love the league and enjoy it. If it wasn't, you are more prone to dislike it considering it's too different
One thing I hate is the people who had a sudden turn around and only love the Alola league because 'Ash won'. For me that just feels like such a superficial reason disregarding what the league arc was for and did. Sure, it's nice to get more people like it because of that but I much prefer people who like the Alola league because of the way it approached character and storytelling rather just because Ash won
Anyway, Alola league differentiates itself from other leagues because it pays more emphasis and priority to characters, and not just Ash but everyone. To that end they make it as long as it needed to be, show EVERY battle and feature major character moments for everyone. You really wont enjoy the Alola league as much if you're not invested in all the characters/series since the beginning, because it does a wonderful job of bringing things full circle and wrapping them up
Mallow, Lana, Sophocles, Kiawe, Gladion, Guzma, Ash, even James and ofc Kukui all have major storylines that receive good payoff or have major character moments. Guzma's story is my personal favourite out of the bunch
Also, the 'entry requirements' and no '6v6s', the major complaints of Alola league were always such a non issue to me. It's the first league meant to promote the culture of battling in Alola, of course it's not going to have entry requirements. And the main reason of there not being entry requirements was to have the amount of character stories and growth they wanted to showcase for all the characters. Ukw sure, have entry requirements in form of trials or something so only Ash, Illima, Guzma probably will find a way, Kiawe, Lana maybe, Hau and Kukui participate. Sure have some nameless trainers like Katie come in too. That would satisfy the 'oh alola trainers are so weak no entry requirements ' whiners, but man it would be SO UNSATISFACTORY to get results and conclusions from characters in which there is ZERO investment, esp with how SM's main liking point is how you like the characters. So yeah, no entry requirements for the win for the story they wanted to tell!! It serviced and made the arc richer rather than conforming to whining power scalers
As for 6v6, I consider Kukui when I talk about Alola league. For me it's still the same arc, the main battle that cements Ash as the champion of Alola in everyone's eyes, as we see in JN as too, and the culmination of it. It felt like the culmination of it too, not Gladion. You don't wanna consider it, fine upto you. I will consider it though because it is THAT story only. And my, 4 episodes for 6v6 is as much as every other series usually had on average for 6v6s in leagues, and we got a flashy and amazing battle. And heck, for only those people who care about battles, sure it may not have been always so flashy but genuinely ignoring Jessie vs James and Ash vs Hau, I found every battle good, with some true standouts like Kiawe vs Acerola, Sophocles vs Kiawe and Lana vs Guzma being so damn fun, the semi finals being hype, the finals being really well done and ofc the stellar Kukui battle which many long term fans consider the best of the best of the series!!!
So yeah, I liked how the league was different , how it serviced the story but still provided the battles albeit in a different format, and ofc while I hate Ash winning being the only reason some people like it, one can't deny Ash winning is hella satisfying not for his character but for his story in alola as a whole. All in all, really strong writing throughout!!
Definitely my second favourite league after Sinnoh, tied with Johto