I'm curious. Why do so many people dislike Best Wishes?
I believe it's mainly Ash being sometimes stupid and lose some battles he should have won and Iris being very annoying to a lot of people. And gen1 people just dislike gen5, misty hits ash with a log it's totally fine, iris calls ash a little kid everyone lose their mind. And yeah, first episode Ash lost to a lvl 5 snivy then first gym battle lost against a simipour ._. Some people find Cilan annoying too, at least a lot of people like Brock way more than Cilan. Trip never had a really good battle with Ash either ._. The serperior makes no sense, fast as a heck but always get one shotted somehow. But I think the main reason is Ash being dumber than he is in DP and Iris .-.
To be fair, there is a few key differences between Misty and Iris getting angry at Ash. When Misty did it, it was usually pretty justified due to Ash being such an inexperienced trainer. Admittedly, I don't think that Misty had much experience over Ash at the beginning of the original series, but she was more knowledgeable than he was and calling him out when he made rookie mistakes was understandable. By the time BW came around, Ash had a lot of experience under his belt and trying to do something similar with Iris didn't work. He had too much experience to be dismissed in a similar way to how Misty used to treat him, especially when Iris didn't seem like she was a rookie trainer until her backstory with Excadril was revealed, which still feels pretty forced when you consider how she was depicted for the first chuck of BW. Not to mention Iris calling out Ash on his immaturity just made her look like a giant hypocrite when she was just as immature as Ash, if not more so. I don't think it's a matter of favoritism for Misty. It's more like the key differences between the two characters and their relationships with Ash made the final results significantly different. It was basically way too late to try to recreate a similar dynamic that Ash and Misty had in Kanto, especially when it was primarily one sided with Iris belittling Ash with Ash rarely reacting to it. It was pretty rare whenever anyone reacted to Iris's catchphrase or called her out on being a hypocrite.
As others have pointed out, BW coming off right after DP definitely didn't help its case. I think it would have been poorly received if we got something like BW after AG or even after the OS, but coming off of DP with Ash getting to his then highest rank in a League tournament, defeating what many consider to be his best rival in the anime's run thus far, having some terrific battles, Dawn having the best development out of the female leads and handling Team Galactic so well only made BW's flaws larger for people.
Resetting Ash to make him more of an idiot even when it comes to battles was a terrible choice. Trying to capture a Deerling without battling it didn't bother me so much, but stuff like coming to a Gym battle with only one Pokemon and actually intended to sweep a Gym battle was completely moronic. Even OS Ash wouldn't have pulled a stunt that stupid.
Iris was definitely a huge problem for a lot of people, myself included. She came off annoying, just forced herself into the group and despite most of early BW giving the impression that she was a rookie trainer, she somehow turned out to be an extra special snowflake Dragon Master in training with special powers and could win nearly a hundred battles before being old enough to become a trainer. This was the same character who couldn't get Axew to learn Dragon Breath for the longest time and couldn't get Excadrill to listen to her for at least a year or two given how small she was in the flashback, but then Axew can learn overpowered moves like Giga Impact or Outrage and she can get an overpowered Dragonite to come along with her easily. All of Iris's accomplishments, aside from Axew learning Dragon Breath possibly, were so forced and undeserved.
Trip was an awful rival, especially after Paul. He felt like a poor attempt to capture that lightening in a bottle again, but making him a rookie trainer was a complete mistake. Despite how bad it was for Pikachu to lose to Snivy in their first battle, I was willing to let that slide at first to see where they were going for their rivalry. When they just wanted to make Ash the underdog of the rivalry again, I tuned out. Much like Iris, Trip would belittle Ash, mainly for making basic comments and for being from Kanto, but Ash didn't really react to it. There wasn't even much of a reason behind their rivalry other than Ash just wanting to battle Trip because he was there. Trip acting as if he was so much more experienced than Ash was definitely a problem.
Battles in general were pretty awful. There were few that really stood out and the Unova League was a complete mess. I didn't mind Ash vs. Trip being a one on one match. They didn't deserve a full battle with how lackluster of a rival Trip was and getting him out of the Unova League was the best choice they could have made by that point. The qualities of the battles themselves, throwing in a filler episode after rushing through most of Unova to get ther and how Ash lost to a moron were pretty huge issues.
The whole Team Plasma issue was another problem people had with BW. Obviously they had to work around the two parter due to the Earthquake, but I think the reason we never saw the two parter had more to do with B2/W2. With a new Team Plasma being introduced there, they might not have wanted to do much with the B/W Team Plasma. It would have been difficult to try to adapt both storylines, especially when the time skip for B2/W2 is kind of important.
Most people didn't care for the Decalore Islands arc since it was mostly filler episodes and Iris and Cilan coming to Kanto didn't really amount to much other than a sudden departure for them. Admittedly, I didn't think that most of the episodes there were that bad, but when they rushed throughout the Unova journey and Episode N only to end the series on a string of filler episodes, it is pretty frustrating.
There are a lot of problems with BW and like I said before, I think that this would have happened regardless of whether or not it came after DP. It does make some of the problems more obvious or possibly worse than they would have been, but it still probably wouldn't have been so well received among fans.
