Not sure if this has been discussed before but didn't see anything when I did a search.
To you, what is the best sounding engine spool up?
For me personally, it's any 777 with a GE90 engine.
There is a great example of this on the following video on Flightlevel350. It's of Continental's Peter Max taxiing into position and spooling up for it's take-off roll. It's probably my favorite video on the site.
Just an awesome sound and better than any existing sports car in my opinion. Just never seem to get tired of hearing it.
So what about your favorite?