Most of us are going to say Greddy EVO. Because it has an nice deep sound and a pretty nice apperance. But I think that If you get the evo you need to do a dual conversion which I think is pointless. I say go with the Tanabe RM, I have it on my car and love it, its nice and deep and not as loud as people say. Also the Apex WS, 5Zigen fireball, and some others are nice. I notice the RSX type-S muffler has been getting popular with the Accords now.
Jon