Ruby/Sapphire.
skipped over gen 4 completely, dabbled in 5, and have yet to play gen 6 or 7. When I have an itch to play pokemon I play that smogon competitive battle simulator thing online, which is free and covers 99% of the excitement I have in Pokemon (Since the stories are garbage and GameFreak insists on making annoying Anime-ish characters and forced legendaries. Why even bother with the real game)