If it's combat over graphics, then Persona 4 is your choice. In 4, you can control every one of your characters and choose what abilities they get and lose. If you buy Persona 3, make sure to buy the FES version, it has the epilogue and bonus content. The Portable version uses the combat system of 4, so it may be your best choice as well; it also lets you play as a female, has a brand-new difficulty, and lets you customize your Personas with "skill cards". The graphics take a hit as I said and there are speech errors, but I think it's a solid game. Difficulty-wise, I'd say Persona 4 is harder than Persona 3 because the items are more scarce and the enemies are harder.