Very interesting thread. Please allow me to add my top three.
(in no particular order, they all are tops in my book, can't really put one over the other)
1. Bleu Cheese x Sour Diesel (breeder unknown) Really had a sour smell like a bleu cheese mixed w diesel fuel, great high, very sativa up front and then a long lasting heady trippy yet indica relaxed buzz. Breeder unknown
2. Grandaddy Purp. Buddy of mine drove over 1,000 mi to NorCal to get the clone. It was worth the trip. Smelled grapey, tasted grapey, grape color stripe on the stem, great stone.
3. The REAL G-13 over 10 years ago. Still to this day the most unbelievable nuggs I have ever smoked.
Honorable mention:
I HAVE to put Mr. Nice's Super Silver Haze up there too. LOVE IT.
Also,
White Rhino (unknown breeder, over 10 yrs ago)
Bubble Gum (back in 1999) (seriously some sticky-icky dank bomb!)