My favorite overall strain for general use, especially during the day, is Sour Diesel. True Sour Diesel is very consistent, although many people try to pass off lower quality product as SD because the name is so recognizable. The smell is a dead giveaway, very unique. Even the very good NYC Diesel and Lemon Diesel strains have a slightly different odor.
For nighttime use or when I just want to get totally gone, Death Star is great. Sour Diesel crossed with Sensi Star, with a powerhouse Sativa and Indica as parents you know the kid is going to be beautiful.
On my Legendary List are a few strains I was only able to get once at a high quality. All other times I found them from different growers they were good but nothing special:
Alaskan Thunderfuck circa 1999, Sensi Star circa 2001, and some strain I don't even know the name of circa 2009. That last one was nicknamed Supernatural because that kind of quality just shouldn't be able to exist in Nature. That one is the best I've had by far, I happened to have a passing acquaintance with the grower, who always had great quality, but the Supernatural was something else completely.