It's not really hard to pick one, because my favourite game of all time is also the ultimate RPG for me as well.
I'm talking about Lufia II: Rise of the Sinistrals. It has it all, amazing gameplay, an epic and actually thought provoking storyline, memorable characters and interactions, expansive world with tons of things to do, some actually difficult puzzles with great use of on-the-fly abilities and scenario, on-screen enemies plus the game was actually challenging (unless, of course, you overlevelled, which destroys the challenge of any RPG). And all this great package can be found on a SNES cartridge 
.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
