Audio first all the way, well worth the money in my opinion. Just so many little features that you didn't think you needed that makes it a more pleasurable journey
e.g. Remember in parents car, tomtom on the windscreen and radio playing, tomtom says a direction and no one hears it because of the radio. Pioneer = automute
People with slow cars will always say Audio. lol
Only because we can't really make a significant difference with performance bits
but even with a quick car, still would say audio