Wow! You started quite the the popular thread SSBUSDRVR! I like it!
As for favorite engine sound: For me, nothing raises the hair on the back of my neck like a good ole' Rolls Royce Merlin. Our Camaro club had an outing to the Air Museum in Everett when they brought their Mustangs out to fly. I went more to get my fix of that rare sound than anything else.
In a related anecdote: Years ago I was inside at work in Auburn,WA, when my ears picked up that familiar sound. My shop was under the local airport's pattern, so I got used to airplane noise. But I knew what this was! I ran outside fully expecting to be rewarded with the sight of a P-51 overhead. What I saw when I got out into the light was even better- and rarer: The unmistakable elliptical wings of a Spitfire roaring down the valley. For a guy like me that was darn near a religious experience!
