I never properly gave my thoughts here, huh.
1. SM - Pros: I love the vibes, TRio is at their best in this series, Ash's best team is here, it has multiple characters I like a lot (Kukui, Kiawe, Lillie, Gladion, Guzma), and just as important, I don't dislike any of the major characters. Bonus: Ash vs Kukui is my favorite battle in the series. Cons: The shift in artstyle is definitely jarring, especially for Ash. SM Ash also has a fair share of OOC moments.
2. DP - Pros: Paul is still the best rival, and Dawn is the best human companion. Sinnoh League is still the best league, Ash vs Paul at the Sinnoh League is one of the best battles in the series, and DP Contests massively improved on the concept from AG. Cons: Filler is awful, and there's a lot of it. Team Galactic is a snooze fest.
3. XY - Pros: 3D animated battles are godly. The Mega Evolution Specials are GOAT. Hawlucha. Cons: Bonnie is annoying. Serena is wasted by Showcases being trash, and Amour is a detriment to her character. Sawyer is unbelievably rushed from complete newb to E4/Champion level. Kalos League is rushed through for another mediocre villain arc. Filler here is the worst in the series, but at least there's not a lot of it.
4. JN - Still in progress. I like the continuity with other series. Notably, Iris, Gary, Sophocles, and Serena all got pretty good returns. I don't feel particularly strongly about Goh, his "catch-em all" goal, or Project Mew. If the Masters 8 tournament can deliver on its hype, JN will move up next to DP and XY. Otherwise, it falls to the bottom tier.
The bottom three are all honestly about the same level for me.
5. AG - Battle Frontier was a great arc, and the Hoenn League was decent. Hoenn itself ranges from bad to forgettable. May was an acceptable first try to having a companion with equal importance to Ash. At least she was an upgrade from Misty.
6. OS - Kanto is carried by the 4Kids dub and nostalgia. The only good parts of OI are the final gym (first double battle in the franchise!), Charizard Chills, and the battle with Drake. Johto is mostly forgettable, bar the Whirl Cup and the Johto League. (Actually, the Whirl Cup was my introduction to Pokémon.)
7. BW - I liked that all three MCs had rivals, and everyone getting together to compete in the occasional tournament that popped up was great. The dynamic between the MC trio was also pretty fun. But between the surprise of B2W2, unfortunate natural disasters, and questionable (probably executive) decisions regarding Ash's skill, this series was really dealt a bad hand.