Being a kid in the late 90s and early 00s, I was infected with Pokémania, too. I cherished the Game Boy games and also loved the first two seasons of the anime. What's more, I even drank a soft drink whose taste I didn't particularly like (Mirinda) just to collect the Pokémon bottle tops that came with it, haha! I still have them, by the way. Eventually, I started to get bored with both the anime and the games because I felt that it's the same thing rehashed again and again (and partly because I thought at the time that I had outgrown it). Also, I didn't like that the music in Ruby and Sapphire sounded more "polished". I guess it's because I'm used to the "rough" themes of the previous generations. The last game I played was Sapphire and the last season I watched was Johto League Champions. My favourite game generation is Gold and Silver (both Johto and Kanto in one game, amazing!) and my favourite season is the very first one (Team Rocket seemed like they could actually steal Pikachu!).
If you enjoyed the Game Boy games but didn't like the anime, you should give Pokémon Origins a try. It's an anime that is much more faithful to the Game Boy games (e.g. no Ash Ketchum!). There are only four episodes, in which they focused on the most interesting parts (departure in Pallet Town; first gym battle in Pewter City; creepy Lavender City with Mr. Fuji, Cubone, Cubone's Mother and Team Rocket Grunts; 1st battle against Giovanni in Silph Co.; 2nd battle against Giovanni in Viridian City gym; final battle against Blue after the Elite Four; Mewtwo). I liked watching it, but I wish there were more episodes.
Pokémon video game music for a rush of nostalgia: https://www.youtube.com/user/pokemonmusicmaster/playlists
Anime has gotten a lot better lately with DP and XY (AG was very good with a second female quest), blip in between with BW but to be fair it was a new director and plan. But overall the story is tighter, more character development, better plots, Developing the Pokémon and evolving more.
I don't know why people are so crazy about Origins. It really makes no sense in a real way (Pokémon just stand there and take damage), literally only Charizard used by Red who was a Mary Sue. But it's "more mature" so I guess that's it.