Actually I loved Johto up until after the Morty Gym Battle. After that one, I found Johto boring. I actually prefer Johto Journeys over Johto League Championship and Master Quest. I'll be honest, the only thing I really liked at all about Master Quest was the Johto League and the awesome Blaziken debut. That was legendary. But if you take the Johto League out of Master Quest, the only thing I really liked would probably had been Casey's final appearance. Shame they didn't do more with her, for what she was she was fun. I also love the episodes with Sakura and her Kimono sisters. I forget if they were in Johto League Championship or Master Quest. Regardless I liked those episodes and loved the Sakura character. When Misty said she would be joining them, I jumped for joy. I wanted to see her and Ash as a tag team to take on all of Johto, and be BFF's with Misty. Why did you tease me writers? Why? Sakura and her Eevee/Espeon would have been epic! Other fillers I like that are overlooked were the Houndour episode. I know it's minor but wasn't that like the first time Ash encountered a Dark Pokemon? I also enjoyed Jigglypuff in that small rivalry with Snubbull when thy fought over the microphone. It was a fillers filler, but I liked it. Johto had some nice episodes that I enjoyed, it's just overall not as good as the other sagas. But I personally think Johto is better then most give it credit for.
RIP anime version of Glovehead. Pokemon Adventures will save you.