Best I've ever had was the Matanuska Thunderfuck, circa 1990.. A school buddy from Fairbanks would have a qp sent to him every semester. For four years, it was exactly the same every time-- light velvet purple buds of medium size, untrimmed so the bud was surrounded in a cocoon of super frosty leaves that were silvery in color. Removing the leaves revealed a bud of bright purple and silver highlights, with a stunning odor. Weed of that caliber was not available at that time, unless you knew the grower. It was so prized that we'd save nugs until the next semester when more would arrive-- I was one of the few who had a full quarter reserved. One time I left a nug out on the table in my room, and one of the RAs on the floor spotted it, picked it up and looked at it, but couldn't identify it as weed because he'd never seen anything like it. We laughed about that for hours.
The high was cerebral, potent but manageable, and super nice, but it was the smell and taste that killed it. You'd hit that thing way more than needed because the smoke was so enjoyable. I've never seen anything like it since.
Edit to add a note about the Malawi brown. That weed came from another friend in boarding school who would have buddies abroad send him weed woven into baskets from Malawi, Africa. It would come in a cob, wrapped in cord that looked like it came from a weed stem, and it was buried in the earth for a year to cure it. The weed was dark brown, black, and red highlights, and was the most potent sativa I've ever seen. I had a lot of it for awhile, and I'd break it out on people who talked big about their tolerance. It looked like Mexi dirt weed, but the smell would warn anyone paying attention to exercise caution. One hit was usually enough to shut people up for a couple hours.