AG was one of the better handled arcs of the series, what are you talking about? May was one of the best developed female companions of the anime, the Contest episodes were the most popular addition to the show, Drew and Harley were the best rivals for a female companion in the series, and Ash became a competent trainer for the first time and evolved almost all his Pokemon. Ash's Hoenn team of Sceptile, Swellow, Corphish, Torkoal and Glalie, (and later Donphan in BF) were among his best teams of the show. We also get to see Ash conquer the Battle Frontier which is the first time Ash won something big since Orange Islands.
Also Brock and Team Rocket were still actually funny in AG, unlike how bland they become in DP and further series.
I do agree that AG is probably a bit better than BW, though not by much. At least AG actually depicted Ash as actually being somewhat of a pro, unlike BW, and at least Ash didn't lose the league in a really humiliating fashion (though I will contend that, barring BW, AG's turnout was the absolute worst). However, the gym battles were poorly handled (I know Ash is supposed to be a veteran trainer, but for goodness sakes, that DOESN'T mean they should have his rookie team practically beat the Gym Leaders that easily. Probably the only Gym Leader who unambiguously actually posed a challenge to Ash was Brawley. That's actually pretty sad, when the GLs of Hoenn were reduced to basically being COTD versions of Team Rocket. Please don't try to claim they had some sort of prodigies or prior experience, so did Kanto's team and Johto's team and Sinnoh's team, yet even they didn't shred their regional GLs like tissue paper.). And quite frankly, having Ash stay at his rank from Johto instead of, you know, actually increasing in rank basically made at least Hoenn, if not AG extremely pointless to watch (since, let's face it, the entire point of the journey is to get stronger, and how can he be considered better than before if he basically didn't even get a better rank than before?), and it also doesn't help that his sole true achievement in the series, beating the Battle Frontier, basically got treated like nothing by Gary with Electivire, and then there's the fact that they decided to replace May after AG with Dawn just to have the latter do what May would have done anyways in terms of goals, which basically meant that all of May's development and creation was effectively made pointless (and honestly, if they aren't even going to bother replacing Ash with the regional male trainer precisely because he's the face of the show allegedly, then why bother replacing May regarding her contest goal? And I don't even like her.). I never really found Brock to be that funny regarding his womanizing gag (actually, it disturbs me that with AG they are reducing him to a Glenn Quagmire character), and in fact, he proved to be even more useless than in Johto (and let me tell you, he barely had a use when he managed to do that contest in Beauty and the Breeder, and didn't focus on having his Pokémon mate or even raising eggs during Johto, despite the breeding mechanic being introduced in GSC). I also thought the inclusion of contests was pointless anyways, especially when the contests in the games not only don't even lead to the end credits, they don't even contribute to the main plot at all (in fact, they really don't contribute much other than possibly evolving Feebas into a Milotic). And anyways, if they were really that popular, please explain why they were cut out by the time of Best Wishes? Lastly, I actually found Team Rocket's presence to be extremely pointless, and in fact, arguably AG ruined them. Honestly, at least in the Original Series, while they were comical, they did actually prove to be genuine threats most of the time. In AG, they were more like nuisances, not even remotely threatening. They didn't even get serious until BW, and even that was basically mangled. In fact, Takeshi Shudo should have replaced Team Rocket instead of Misty. As far as how you can replace them, simple: have Team Magma (the entire organization I mean) try to abduct Pikachu so they could force-feed it the Red Orb, viewing him as a suitable host for awakening Groudon (since the Magma vs. Aqua arc did have Pikachu becoming possessed by the orb). If you're going to have a recurring main antagonist, you need to make sure they actually qualify as a threat, whether they are comical or not. The Joker is quite comical, yet he actually proves himself to be a threat. General Blue was very hilarious, yet he actually proved to be a threat to the characters. JJM in AG and DP didn't even qualify as actual threats, focusing far too much on being comedians than, you know, actual villains.
As for BW, honestly, depicting Ash as being a huge manchild (heck, even keeping Ash in the first place since it was supposed to be a reset) and a total idiot even for him (Indigo League Ash at least had the excuse of being a rookie, BW Ash didn't), treating the GLs in an even worse manner than Hoenn, and having him actually bomb the Unova League (and to a guy who rivals even BW Ash in terms of idiocy), plus having Pikachu lose to a guy he frankly could not lose to in any way (Trip) and actually skipping the World Conference tournament which not only would have actually advertised B2W2 to some extent, but would have either ensured a return for Misty, or even give her a far better finale and true closure than in either OS or AG, plus having Dawn's cameo be utterly pointless (May at least had a transregional ribbon she could get in Sinnoh for her Johto trek as an excuse for her appearance in DP. Unova doesn't even have Pokémon Contests, so Dawn had zero business in Unova anyways) was just bad, and thus has BW being bar none the worst series ever. That being said, there were some good things about it: They did do Iris decently, not to mention when she left, they clearly learned from their mistake regarding Misty's departure and made sure she pursued her goal instead of being forced into a gym. Charizard not only returned, but was even made a semi-permanent roster of Ash's, and they did reference Ash's old team a lot.
XY did at least improve Ash quite a bit, though I'm not so sure about how they handled Serena (she barely had more of a reason to travel at all than May ever did [as May was travelling despite hating Pokémon, meaning she literally had no real reason to get into the Pokémon training enterprise in the first place, let alone travel with Ash], even if it was only because she was Ash's old friend, which isn't even that accurate anyways, and they barely even gave her a real goal until... what? A few episodes back? At least with Misty, she wanted to become a Water Pokémon Master to prove her worth to her spoiled sisters, Dawn wanted to follow in her mom's footsteps as a Pokémon Coordinator, and Iris wanted to prove herself to her community). And from what I can gather, it's at least doing some things better than with BW. Unfortunately, it's not enough to actually save it from being a ratings disaster. As far as me, I won't have any reason to watch the anime until Misty actually gets a proper return, and especially is actually allowed to pursue her goal instead of being forced into the gym.
X and Y was a top notch, comparing to BW. I mean, we're being a bit too unfair with unfair with BW. Both Cilan and Iris were good companions, but Ash was literally the worst Ash of all the series ever.
I particularly enjoyed Iris,she was a good character tbh. And I don't think BW was the worst one, I think AG was even worst than the Best wishes.
I'm sorry but I think you should watch Advanced Generations again and compare them to Best wishes. Best wishes is miles better.
I don't know about whether AG is "worse" than Best Wishes (personally, I rank it slightly better, although only because Ash didn't come across as a huge retard in that saga, and Ash at least retained his rank instead of bombing the league), but I do agree that AG is actually quite close to it in regards to it being very bad. It's funny, people complain about Johto's use of fillers, yet if anything, AG felt more like a filler saga, especially when Ash doesn't even increase his ranking in the leagues (at least Johto actually had him doing far better in the Silver Conference than he did at the Indigo League, not just in ranking, but also overall since he actually managed to fight his rival and beat him). And that's just the tip of the iceberg, unfortunately.