Thank you for the other suggestions guys, I never expected so much help tbh and this was a big shock to me so I am very grateful.

I did consider Pokemon but while I might have some fun with it, I don't personally feel I could really commit to running that game. Although with FFXV and Nier: Automata they do look like something I might be looking for so I will give those a look as well. I have managed to narrow down the list as well so slowly getting there lol. (To those interested in the list it's between FF9 or Kingdom Hearts, FF4 too if I can find a fairly cheap SNES and copy of the game).

Speaking of Sonic and RPGs, there's actually a Sonic RPG on Nintendo DS (Sonic Chronicles) that can be done in less than 3h (even 2h in NG+ category). As weird the combination of Sonic universe and RPG gameplay can be, it's not even a bad game. Too bad I gave my DS to my little brother a few years ago :p Maybe I will try an emulator to run it.