I'd say PS2, although I really adore the DS and 3DS lineups. Probably like the 3DS lineup even more than the DS one. Why haven't you included that?
I mean its got:
-Bravely Default
-Bravely Second
-Persona Q
-Kingdom Hearts: Dream Drop Distance
-Shin Megami Tensei IV
-Shin Megami Tensei IV Final
-Devil Survivor: Overclocked
-Devil Survivor 2: Record Breaker
-Devil Summoner: Soul Hackers
-Xenoblade Chronicles 3D
-Fire Emblem Awakening
-Fire Emblem Fates
-Project x Zone
-Project x Zone 2
-Yokai Watch
-Etrian Odyssey IV
-Etrian Odyssey Untold: The Milennium Girl
-Etrian Odyssey Untold 2: The Fafnir Knight
-Moco Moco Friends
-Legend of Legacy
-Pokemon X/Y
-Pokemon ORAS
-Pokemon Mystery Dungeon: Gates to Infinity
-Pokemon Super Mystery Dungeon
Also, don't forget about Kingdom Hearts RE: Chain of Memories on PS2. That game was pretty great.
Does Tail Concerto really count as an RPG? I figured it was more of just a 3D platformer.