I mean, my favorite game is probably persona 5. Which I think could definitely be up there for JRPGs along with some of the final fantasy games (I would say X but popular opinion would say 7) or a dragon quest game.
Mario or pokemon (gold/silver imo) are probably the most iconic if you want to put those into discussion.
In terms of mass appeal maybe mine craft?
GTA V keeps getting re-released on every platform along with skyrim so one of those could definitely be considered I would think.
Roblox babyy. Nah, just kidding. There are to many in each own unique style. We need to account for player base, style, art, mechanics and so on to have an objective view. But skyrim sure is a contender