Hey, ever heard of an opinion? Let me tell you why Diamond & Pearl was okay to me. First as I stated, Ash was pretty smart at battling in this series. The contests focused on a variety of ways for Ash to dominate his opponents, and the pretty light show wasn't so bad either. To me, Pokemon Contests shows more of a Pokemon potential to unleash some pretty awesome combos that way it can utilize their moveset more. When I watch the anime, I tend to forget all about the PKMN games & put myself in a Pokemon world. D&P shows more of what a Pokemon can do and I find it pretty interesting.
However, I give D&P some criticisms. To start, Team Rocket was extremely annoying in that series. For once, I would like a plot without them in it. They're not even funny to me anymore. It's like the writers are forcing them down our throats and only have a few episodes focused on them that are actually good. At this point, I wish Bootch (I mean Butch) & Cassidy could replace them. Imo, I find them much more entertaining than those two. The show would feel much more refreshing with those two around.
Second, some of the animation look pretty bad & some of the episodes feel pretty rushed; or they're mainly bad fillers, s that's the only criticism I can think of for the show. I like Dawn. Her voice is pretty adorbs, not to mention her look too. Probably the cutest Pokegirl in the show, but her mom looks like a talking Oran Berry tho'. Anyways, she helped Ash a lot on how to execute contest moves in order to gain the advantage when facing his opponents, which is why I said Ash was smart in his battles again in the first place. He's the only one to beat a freakin' Darkrai and almost fainted Latios. You gotta give him & Dawn's lessons for that.
OH. While I was writing, I just thought of a 3rd criticism - Piplup. Yup, that little penguin annoyed the living crap out of me. Anyways, I'ma stop from here since we're not talking about what the OP asked. Anyways, OP. If you wanna watch Best Wishes, go ahead. To me, the only good part about that show is the villains and Team Rocket being more serious. XY: The Series is a much better show though imo, so if you want my recommendation, I'd skip B&W and heads toward XY. There's a reason why so many people disliked Black & White and only a few defends it.