i would get one with rear inputs. Mine has front input and I currently have to have a wire that runs up to there, tacky looking. I just bought a cable that will convert the rear CD changer into two RCA's so I can eliminate the front cable but that was $30. Would have been nice if the HU had rears all ready.
If I were to replace mine I would also get one that had built in bluetooth. I have yet to find a decent program that works with my phone.
I'm big on having a HU myself. I like to be able to have tunes when the computer is down, or being upgraded. Also like having the volume knob so I don't have to use the touch screen as much.