It's a tie between 3-4 and 3-5. Although Phoenix was soo sweet, soo funny and soo sarcastic, I just loved playing with Mia more.
And come on, 3-4 is the case where it's like OMG is that Godot? And then OMG he's holding a coffee cup and OMG the theme is playing and OMG young Edgey and OMG it's Dahlia! It was just so...awesome. And the ending really made me cry.
Mia's cases are smaller and I think that's why I like them more. Just like how it used to be: Gumshoe, witness-turned-murderer, defendant, victim, judge, and two attorneys.
Playing as Edgeworth in 3-5 was amazing, though. And Godot! heart
The Phoenix Wright/Gyakuten Saiban Guild of GAIA