Several answers of the many. First is a Cuban that happens to be my favorite. Monte Cristo #2. I had a great connection at the time. I had bought 6 boxes in 1987 and in the early 90s all Cubans took a big hit. I think it was a hurricane but I'm not positive. But I gave them after 3 years to replenish my supply and the taste had changed big time. I've tried them several times over the years and they've never returned to the cigars they once were. They are good but not great. I have 3 and a piece boxes ot 1987 stash left and I smoke one or two a year. No they aren't for sale as they can't be replaced.
Number two is more recent. Olivia O's. Since the sale of the company they have really improved. I'd tried some since they came out, I've been smoking cigars for 40+ years, and and never really liked them enough to buy them. I tried one that came in a sampler a couple of months ago and man do I like them. I've filled a drawer in my humidor (100) to age and won't touch them for 5 years. I've got a box to smoke in one of my tupidors and buy more when when I get a deal.
I age alot of cigars and replace them when I've smoked them. I notice small changes to them yearly. Most of the time with premium brands it's very subtle but it's there. There been a few that the decline was so great that I quit buying them but I haven't had that happen but a couple times over the years. You have to except that with a weather effective crop and hand made products. It's part of the hobby.