If it's popular I would eliminate niche from the list. The distribution of niche is so small relative to designers. If you've encountered it several times, I'll bet anything it's a designer fragrance. I thought perhaps Bel Ami, but that doesn't contain musk. Aramis original has loads of leather and musk, but also patchouli. Could it be Fahrenheit, which has healthy doses of leather and musk, as well as being quite popular? But then, Fahrenheit was never known as elegant. A rabble-rouser, if anything. Anyway... would be interesting to know what this mystery fragrance turns out to be.