It typically changes from time to time, but since I played it for the first time, Disgaea 5 had a special place in my heart. Nowadays, I sometimes wonder if Disgaea 4 is better. It's difficult to decide, I'd say they're objectively equal, with D4 having better story and dialogue then 5 but the other has better gameplay and replayability.
Others I've enjoyed immensely, especially based on playtime, are Super Pokemon Rumble and Hyrule Warriors, though they're the kinds of games I need to be in a specific mood to enjoy. I've always enjoyed beat-'em-ups but unlike SRPGs in Disgaea's case, I can't think of any that are particularly better than the others. They all feel somewhat the same to me.
Used to absolutely love Skylanders, as well, but that was overpriced and had barely any replay value. Nowadays I'm not such a big fan of the series. In fact, I wish I never spent so much money on it at all.