I'll recommend Disgaea series if you like SRPG, grinding, character/weapon customization, great story and humour!
Max level 9999 + Reincarnation = Inf. Levels? ^^

Also Zettai Hero Project: Unlosing Ranger VS Darkdeath Evilman (PSP), by the same company who made Disgaea
http://www.youtube.com/watch?v=8wn6NYU7QeU