I play quite a bit of games hardcore through out the years but the stand outs are....
Street Fighter and Both Devil May Cry Series
Im a Tourney SF 2, Alpha and 4 player.... Unfortunatly not 3 :( even though i love 3
I also play MVC, Tekken and KOF
I have 100% complete beating on all difficulties and bloody palace in all DMC games from 1-4 (yes even 2.....) and DmC with SSS rankings
back in my prime i even beat DMC3 on DWD mode which is a fan made up mode where you played DMD (the highest difficulty) from a new game (meaning you start the game from scratch with out new game plus)
As for RPGs
i played the Suikoden series from 1-3 pretty hardcore back in the day collecting all 108 characters in all games....haven't bothered with the new Suikoden games though.