I have tried MANY, MANY different types of beers over the last 40 years - too many to list.
That said, I will cite 2 categories: Best Ever AT THE TIME I TASTED THEM, and Most Memorable OTHER THAN THE BEST.
Best Ever (not saying these are the best beers NOW, but just at the time I tasted them I thought they were the best ever), in order of WHEN I tried them:
1) 1984: Molsen Canadian ... Not Molsen Golden Ale (which was or is a great beer), but Molsen Canadian, their regular beer. I had my first bottle of Molsen Canadian in Greece, actually, in the Summer of 1984. Here is the big thing: It was NOT pasteurized. You could get Molsen Canadians in the US, but those had to be pasteurized. The non-pasteurized Molsen Canadian beers were simply amazing. What is wierd is that I visited Canada quite a bit prior to 1984, but for some reason never had a Molsen Canadian, just the Molsen Golden Ale.
2) 1985: Anchor Steam, on tap, in San Francisco ... actually in Palo Alto at the Stanford student bar. Now you can get Anchor Steam many places, but back then, like Coors, you could only get it locally (i.e. in Northern California for Anchor Steam, and in the Mountain States for Coors). Anchor Steam was marketed like a craft beer back then - and could not "keep" when transported long distances - though there was ONE beer store in Manhattan (on 86th and Amsterdam - long since closed), which upon my request, was able to get a special shipment, 1 case per quarter. Anyway, when I first had Anchor Steam, on tap ... WOW ... that was the most amazing beer I had ever tasted - and that remains my most unique tasting experience. Anchor Steam is brewed - or was back then - very differently from most beers, and the blend of amazing SMOOTHNESS, but also the almost CHEWY hops taste, is unique, especially on tap, in my opinion. Anchor Steam, back then was as smooth as a beer such as Heinecken, but close to the bitterness of a good Ale, and as chewy as a heavier or amber Ale. Unique.
3) 1987: Pilsner Urquel. I cannot remember the EXACT event at which I tasted this, but it was the best lager (pilsner beers are types of lager beers) beer I have ever tasted - and really one of the few lagers I actually like. Generally, I find lagers to be both crisper and smoother than ales - and I do not generally enjoy that. But Pilsner Urquel was - and remains - one of the finest beers in the world, in my opinion.
Most Memorable - other than the above - these three have a story behind them - and are both awful beers, but cheap and with a story that means something to me personally:
1) 1982: Red White and Blue. My beer of choice to buy when visiting my best friend at UVA in college. You could buy a case for $6 - cans though. Terrible beer, but cheap, cheap and cheap ... we used to cool them by submerging several 6 packs at a time in his Uncle's pond (his Uncle had a 4-acre place, with a pond) just outside of Charlottesville, and get completely wasted on case, after case.
2) 1980-1983: Mickey's Big Mouths. Just awful beer, as bad or worse than Red White and Blues. They came in bottles - but not standard dimension bottles. They were about 1/2 to 2/3 the height of a regular beer bottle, but really wide, with a really wide mouth ... and extremely cheap. Why buy them? Not only were they cheap - which going to college in NYC made a difference - but because of the extra-ordinarily wide mouth of the bottle you could chug a single bottle in nano-seconds, it seemed ... so you could get drunker faster.
3) 1990: Iron City. Another bad beer - though much better than the other 2 cited just above. I lost a bet to a client who lived in Pittsburgh, and the condition of the bet was I had to get him a case of Iron City and personally deliver it to him.. Back then, no internet, and Iron City was only sold in or around Pittsburgh, while I lived in NYC and rarely got to Pittsburgh. It too a LOT of effort to find a case, and even more effort to personally deliver it.