I have used Eternity since it's inception and the formula has changed thru the years and it no longer smells like the original. The current Coty version is just a shell of it's former self. I doubt if I will buy it again after all these years. The Unilever version is "closer" to the original but has no lasting quality at all. The CKCC version is the "original" when Calvin owner the cosmetics division outright. This was not profitable so he sold it to Unilever.
I have sought out the CKCC version and have found and purchased splash bottles from a local perfume store. The problem is that the bottles now have become so old that they have gone "off" a bit and don't smell the same either. I find the Unilever version is the most pleasing scent of the choices available.
Hope this helps.