My all time favorite game is probably Dark Cloud 2. I can replay that game at any given point and still have a lot of fun!!
I also enjoy the Persona series (though, I still haven't managed to play the first original 2...er 3?). Been playing through 5 in high speed, and I constantly have playthroughs going of various Persona titles. I'm also working on Persona Q right now.
Also a big fan of hack and slash titles, my go to series being Devil May Cry. I mostly play the reboot these days though, not that I don't love all the others, I'm just a huge fan of the faster pace the new one has.
I just really love video games, so my favorites switch a lot, but those are three series I can always switch back to and enjoy thoroughly!!!
(I also play a lot of the new DOOM)