To me the originals were amazing, but Gold and Silver took it so much further. Doubling the size of the game, giving you the chance to see what happened to Team Rocket, fighting Red/Ash atop Mount Silver, the red Gyrados, the radio stations, everything was turned up to eleven on those games. It took the concept to heights that as I kid I didn't think were possible. I remember the clock system and staying up late every Sunday until I found my way through those caves to finally find Lapras after a friend clued me in.
Since then the series has only taken incremental steps forward. Ruby and Sapphire were great, but weren't anywhere near as close a step forward as Gold and Silver were. There have been some great enhancemets to the series since, such as online trading and battling, but nothing ever felt as grand as that first huge leap from what was one of the defining games of our childhoods to something beyond all imagination. These days the advancements are so small I don't even notice them. Rotation battles are pointless since there are what, about half a dozen of them in total? Double wild encounters is nothing truly revolutionary, it's merely neat. I miss the feeling of real discovery and the community that was built by kids trading the latest secrets in the playground the next day. Getting a phone call telling you that there was a swarm of Dunsparce ripe for capture and bragging about finding a shiny pokemon, those where the days.
Do it one last time, Nintendo. Make the next game such a huge leap forward that today's complacent gamers won't know what hit 'em.