Joining a forum like Basenotes can keep you abreast of reformulations. They're a very fussy bunch on there (a whole forum section dedicated to Aventus batches) but knowledgeable.
Helped me train my nose; I purchased Dior Homme Parfum on a whim, and what I emphatically called "Coca Cola" notes were actually iris apparently.
I wouldn't say I have a top five but my absolute favourite remains Scent Intense by Costume National. It's a gothic cathedral drowned in purple light. If Count Dracula were a DJ he'd wear Scent Intense.
I wear it only when I'm at my absolute best, have a full bottle and another full limited edition bottle with myrrh. Lasts for two full days on my skin. Comes packaged with an anal toy which came in useful back before my operation when my testosterone was high. I should use ED drugs I guess.
Other favourites include Donna Karan For Men, extremely hard to find today as it went out of production decades ago I believe. I hoard my bottle religiously. It's a very deep, fruity scent with an exotic edge. Mysterious. Seductive.
For partying it's gotta be Aramis Havana. It smells exactly as you'd expect, with tangy tobacco notes. I have a vintage splash bottle.