I've had Glenlivet 12, 15 French Oak, 16 Nadurra, 18, 21, and 25. For my money, the 18 is the best buy. The 21 isn't a whole lot different from the 18, in my opinion. You can look up various experts' reviews and they'll disagree on which of the two has the higher score, the 18 or 21. I bought a bottle of the 21 a few years ago when it was just over $100 (US), and shortly after that they upgraded the packaging and raised the price substantially. The 18 is now less than half the price of the 21, and so it's not a hard decision for me. Everybody loves Macallan, but I tend to get tired of it long before I finish a bottle, so I'd go for The Glenlivet if it was up to me. For the price of the Macallan 18, you could get both Glenlivet 18 and and 21 and judge for yourself!