Games: Red, Blue and Yellow (Plus Green in Japan)
That's right! The originals slide in at #2.
To begin, these games kicked off this amazing franchise. Everything that is Pokemon started with Red and Blue (Green for Japanese players) and they set in place formulas that we still follow today, just on a very basic scale.
Story wise this game is just classic. The gym leaders were memorable (to be fair, they were the originals) and the Champion was your rival you had worked so hard to beat, and the ending was just satisfying. Team Rocket is easily one of the best villainous teams, and their leader was secretly the last Gym Leader! What a twist!
It's hard to praise this game without sounding like a genwunner (people who think anything past Gen I is crap), but I loved it! It was definitely one of the best features of my childhood, and to this day I still enjoy digging out my copy of Red and jumping right back in.
Favorite Pokemon from this Generation:
Charizard, Gengar, Nidoking, Lapras, Kabutops, Mewtwo, Hitmonlee, Jolteon... The list goes on!
Team I used my first playthrough:
Charizard, Gengar, Nidoking, Lapras, Hitmonlee, and Jolteon