Ah here we go again bashing the alola league while overrating the crap out of other leagues
The Sinnoh league is definitely the best league in the anime, there should be no debate about that. It perfectly showed Ash growth from OS till now, him using reserves was an excellent idea, and no they didnt overshadow the rest of the team
Gible did well against Conway and Tobias
and the rest of the sinnoh team was used in the battle against Paul, still the most satisfying storyline Pokemon has done
For my second spot its Johto and Alola tied. Johto is the only league where Ash's loss made sense and wasnt poorly written plus i loved how it was more than just elmination. Ash vs Gary is a poor rivalry but the battle between them was good and even if it was last moment, the rivalry concluded greatly.
As for Alola im tired of people calling it crap because it had no entry requirements and no 6v6 battles. First of all Ash vs Kukui is part of the alola league, its part of the league arc and so i consider it when talking about the alola league. Considering it was the first league no entry requirements makes perfect sense, especially regarding kukui's goal with the league. Plus the battle royale weeded out weak trainers anyway. The emphasis on the league itself, where EVERY battle was shown and 18 freaking episodes were dedicated to fully show it, i love that so much. It felt respectful to the league, giving the arc the proper focus it needs. Unlike the blatant disrespect of Unova and Kalos where in the former they give ash such a bs defeat and then continue on with arcs making the unova league look like another Don George tournament while the Kalos league rushes all the battles to give the TF arc the climax of the story. The character driven story of the alola league is something i admire very much, it wasnt just ash, it had character development for so many other characters. The Guzma storyline was done amazingly imo, yes its different from the games, and considering the lore, it made perfect sense for me. Alola was a region Ash deserved to win the league in, it was more important of a region to Ash and he fully embraced and learned about its cultures, traditions, becoming truly one with alola. There were so many good battles like Ash vs gladion, ash vs guzma, kiawe vs gladion, guzma vs lana, guzma vs ilima, acerola vs kiawe, kiawe vs sophocles. The TR battle was the only battle i heavily disliked. Ash vs Hau doesnt bother me as much. And then ash vs kukui, that episode had 4 episodes, the amount of episodes every league 6v6 has had, and it was one hell of a battle perfectly tying together storylines from the first episode. Ash deserved to win this league, idk how that can be questioned.
3rd place would be Kalos simply coz the two battles were amazing. Storywise it was bad, they rushed the hell out of it and it deserved better, but the battles alone make me like it more than hoenn unova kanto. I dislike the latter three and ive stated reasons why multiple times already. Ash vs stephan definitely makes unova above kanto though in my eyes.