The best RPG of all time should be either Ultima IV, Chrono Trigger+, that's it, with the Plus patch or Pokémon Crystal (a hacked ROM) with improving patches, such as:

- all mons ingame

- level cap

- no trading

- improved Battle Tower

Ultima VII shines with the in-game simulation, but today Cataclysm DDA:Bright Nights curb-stomps U VII in that area. Pokémon, well, it's about battling with your favourite mons, the game story it's just a placeholder with nice Japanese pixelated vistas.

Also, I'd put Slashem on par, too. Because it's damn silly and fun to raise a Samurai with Yakuza weapons, an anachronistic madness like the Discworld series (and OFC you have the Tourist role from the books too). More than strategy, Slashem/Nethack it's about lateral thinking and doing crazy stuff to advance into your goal. Throwing potions as weapons? Done. A Doppleganger Kung Fu monk doing DBZ-like attacks while using your Wand of Digging against rock based foes? OFC, done.