We'll the game Ive played the most is World of Warcraft. Not because of the game itself, but because of its community.
I cant really decide upon the GREATEST game tho, since in all honesty games like Final Fantasy 7 got to me at a time where the epicness was built up by the fact that I was so young.
The game thats really set the benchmark for RPGs for me. Its not your traditional JRPG, its more than that. The story is heartbreaking while believable and breathtaking. The gameplay is mindblowing, more to do than you could ever wish for in a game. The graphics is timeless really, and the soundtrack is something to die for. Listen to this fight-theme vs the vampire-lord in the game: http://www.youtube.com/watch?v=aXuJ2cHx7Aw
Suikoden neclord theme. Its like a breath of fire, AND a final fantasy AND vandal hearts.
Special mention ->Final Fantasy 7:
The only game that made me cry. Goosebumps incoming. http://www.youtube.com/watch?v=12vlUlLQpQg
Action/RPG:Castlevania Curse of Darkness:
Yes you heard me. The ****ty xbox game every diehard castlevania fan hated is my favorite Action/RPG-game. The game didnt have much of castlevania in it. It wasnt a sidescroller (Symphony of the night should get a shout-out here), it didnt have your Alucard or a badass Belmon running around whipping stuff to death. It wasnt really a castlevania game at all. It did, however, have the best character-development system I've ever come across. You customized your character based upon what you liked, not depedning on what "phat lewt" you came about. I can promise everyone here that nobody used the same exact gear/summons etc.
All that with a whole new soundtrack, not based upon castlevania but just as good. A new character almost as pity-worthy and furiously awesome as a Belmont... or so you thought, untill Mr. Belmont came about to show you otherwise. http://www.youtube.com/watch?v=vz8DH30l2_E
Love it or hate it, best Action/RPG ever.
Action:Devil May Cry 3:
So youre eating a slice of pizza minding your own business when the world ends and hell comes to earth. Imagine that. Dante does what every other unbelivably awesome guy does; brings a 5 foot 500 pound Sword to change those things. The game's not really that hard to grasp. Take the only path you can forward, kill all enemies, pick up the orbs flying about untill the game ends.
But what a ride.
The thing about this game is that it only really has 1 attack button, 1 jump button, 1 shoot button and 1 special button, but theres approximately 500000000000 attacks and combos you can string together. After 1 playthrough on hard you can finish the game without ever getting hit. You progress by being a better player, and the controls are so intuative that while you were struggeling with facing 2 enemies in the beginning of the game, you will be able to fly through a room containing 500 enemies anime-naruto-bleach-kungfu-style, slicing through them all without taking a single scratch and without ever touching the floor by just pressing that 1 attack button at the end of the game (granted, youll have to switch weapons and whatnot). I mean, being able to kicking an enemy over, curbstomping it while skateboarding in by enemies... Kratos is such a *****.
Oh, did I mention you get to play the game as the most badass character in any game ever if you finish it? Vergil is the most awesome thing ever created.