My subjective top 5 are:
1: DCC: It has a sublime ride for a car like this when in Comfort mode. I have too large a beer belly to be thrown about on a daily basis these days, and everything sharpens up nicely in the other modes when I feel like it.
2: Panoramic roof: It is great having this open, and so little buffeting.
3: Electronic handbrake/hill hold/stop start: I really like this now, but I was initially apprehensive and confused as to how it all worked
4: Dynaudio: The best sound system upgrade I've ever optioned
5: Economy: Faster driving is nearer 35mpg than 30mpg for me - result! The long term average is approaching 37mpg. However, my trips are seldom less than 20 miles
If I could have a sixth choice it would be keyless.