Well, I went down to the den and poked around a bit and found roughly 150. Maybe 15 of those are just sample size. I didn't get any out of storage and I didn't count any Avon (I don't care for Avon aftershave but I wanted a couple of their shaving theme decanters). I also didn't count any of my antique stuff that's long past it's freshness date.
Four? you want just four? and you want the top 4? the Fender Stratocastor?
Don't think I can answer that one.
I can give you a few classics that need to be tried just because but I'm not sure they're the crème de la crème. Plus, as has already been mentioned, scent is a very personal thing. I could also give you some very high quality stellar reputation names but their scents are distinctive so they tend to draw boundary lines between persons. Several folks have mentioned drug store brands that have been popular for generations. Even with those you find strong preferences between brands.
If, as your post says, you are looking to expand your education on aftershaves; might I suggest you expand past four. When I was in aftershave grade school I had four or five but if you want to work on your PhD you'll need to get past 100.

(yeah, I'm going for a double doctorate)
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