Just like the title says. Mine is Skies of Arcadia on the Gamecube.
I would honestly probably have to say Dark Souls above all else - it's the one game that keeps me coming back over and over and over and I just keep falling in love with it every single time!
For me it's a tie between "Sailor Moon: Another Story" and "Vocaloid Holy Harmony" , although I've yet to actually complete "Holy Harmony" to the very end, but I will beat it one day!
"Another Story" took me several years to finish, and I was so happy when I finally did finish it. I'm sure that "Holy Harmony" would feel just as rewarding.
Chrono Trigger. Nuff said.
Dragon Age: Origins you plebeians
Yep, DA:O is a fucking fantastic RPG.
Final Fantasy VII is my favorite game of all time, so it's naturally my favorite RPG. It has everything.
If I were try to make a more interesting choice, maybe I'd pick Custom Robo for the Gamecube.
Dank Souls 3, Mount & Blade Warband
This one is a bit tricky since there are many sub-genres to think about too (JRPG, Action-RPG, Tactical RPG, etc). Since I can't really pick one, here are a bunch of my favorites (In no particular order): Dark Souls, I Am Setsuna, Shadowrun: Dragonfall, Kingdom Hearts 2, Legend of Grimrock 2, Undertale, Valkyrie Chronicles, and The Banner Saga series.