I've never tasted Hibiki (any expression) nor the Signet from Glenmorangie. However, I have had the Glendronach 15yr Revival.
Here was my review of it from 2011:
I am a huge sherry fan. I like big, powerful, sherried whiskies. However, I'm not always in the mood for a cask strength whisky. I was turned on to Glendronach 15yr Revival as being highly rated and one that fit my favorite flavor profile. This is my first Glendronach.
Glendronach 15yr Revival is bottled at 46% ABV, and is a nice copper color.
Nose: Lots of sherry, but a bit wine-like. This reminds me of the Aberlour 15yr Sherry Finish. Chocolate covered strawberries. But, sweeter than that. Maybe Maraschino cherries in a liquid center covered in light chocolate. A bit "too" sweet for my nose. But there is something darker in there. I'm not sure if smoke is the right word, but definitely a strong malty note.
Palate: Warming in the mouth. Semi-sweet on the tongue. Dark, bitter chocolate. Some burnt toffee.
Finish: More maraschino cherries on the finish. Long finish.
Very good. Perhaps too sweet for my taste. Wow. This is really delicious. I might need something salty to go with this whisky. Obviously the balance isn't the best on this whisky, as it needs something else to round it out. However, it IS delicious, and if you have a sweeter tooth than me, this whisky is for YOU!