You are kidding me... Where is The Witcher 3 in generation 8 in your op... :O

SNES: Chrono Trigger
Megadrive: Shining Force
PSX: Suikoden II
PS2: Star Ocean: Till the End of Time
Gamecube: Skies of Arcadia Legends
PS3: Valkyria Chronicles
Wii: Fire Emblem Radiant Dawn
X360: Lost Odyssey
GB: Pokemon Blue
GBA: Fire Emblem
PSP: The Legend of Heroes: Trails in the Sky
DS: Dragon Quest V
PSVita: Persona 4 Golden
3DS: Fire Emblem Awakening

Gen 4: Chrono Trigger
Gen 5: Suikoden II
Gen 6: Skies of Arcadia Legends
Gen 7: Valkyria Chronicles

3rd Gen NES: Mother
4th Gen SNES: FFVI
5th Gen PS1: Xenogears
6th Gen PS2. Persona 3 FES
7th Gen Wii: Xenoblade
Portables Vita: Persona 4 Golden

Projected Greatest Game of All Time: Persona 5

By generation:

Gen 3: Final Fantasy III

Gen 4: Final Fantasy VI (Chrono Trigger a close second)

Gen 5: Final Fantasy VII

Gen 6: Deus Ex (I'm cheating here as the PS2 version wasn't great compared to the PC version). If we're going solely by console versions then Star Wars: KoToR

Gen 7: Deus Ex: Human Revolution although Mass Effect 2 and Skyrim are close runners up

Gen 8 (so far): Witcher 3

This is tough:

Gen 3: Final Fantasy, Dragon Warrior 4
Gen 4: FF4, FF6, Chrono Trigger, Dragon Warrior 5
Gen 5: Xenogears, FF7, FF9, Chrono Cross, Wild Arms, Legend of Dragoon
Gen 6: FF12, Skies of Arcadia, Rogue Galaxy, Sudeki, Summoner
Gen 7: Xenoblade, Lost Oddysee, Blue Dragon, Ni No Kuni, Mass Effect
Gen 8: Out of what I have played, I guess FF Type-0. Bloodborne, I guess, but that doesn't feel much like an RPG anymore

PC (cross generational): Septerra Core, Infinity Engine games, Ultima, Morrowind

My list:
Gen 3 - Final Fantasy 3 (Phantasy Star as runner-up)
Gen 4 - Chrono Trigger (Final Fantasy 6 as runner-up)
Gen 5 - Final Fantasy 8 (Suikoden 2 as runner-up)
Gen 6 - Persona 4 (Final Fantasy 10 & Elder Scrolls 3 tied as runners-up)
Gen 7 - Elder Scrolls 5 (Costume Quest as runner-up)
Gen 8 - so far, Child of Light, Undertale, Final Fantasy Type Zero HD & Witcher 3 have all impressed me. Looking forward to the return of DQ & proper FF titles!

OMG if some asshole says FFX for PS2...

Gen 3: Mother
Gen 4: Chronno Trigger
Gen 5: Final Fantasy 9
Gen 6: Paper Mario Thousand-Year Door/ Persona 3
Gen 7: Xenoblade Chronicles/ Skyrim
Gen 8: My hopes are with Xenoblade Chronicles X, by now the best is Undertale.

It's best game from that generation. DWI

Driving under influence?