I haven't tried millennium. I've only been to primeclass and HSBC. These are fairly similar. They don't have any real food, they just have snacks cold sandwiches (cheese tomato sandwich, turkey sandwich). both have some pastries to choose from nothing amazing there. both have an alcohol selection nothing great there. If I didn't have the priority pass membership this year, I would try the millennium lounge (just to see whats in there).

hope that helps.