Sally Hansen is my favorite drugstore nail polish brand because they're affordable, very pigmented, and have a wide variety of colors. Not only do they have their regulars, but they have a bunch of limited edition colors that seem to come out every time I walk into Walgreens and get lucky. I'm not aware of when their limited edition colors come out, but if I did I probably would be on to it... but I must resist the temptation to splurge.
I also love the nail polishes that are available at Forever 21. I do believe they're originally L.A. colors, just repackaged for sale at Forever 21. After all, the polishes that first appeared at the store actually had the original L.A. colors brand name on it. Lately, they've been coming out with more and more colors, and have recently come out with some scented ones that I have yet to try out. However, I haven't seen them locally at any of my Forever 21s; I haven't seen any nail polishes for the longest while now. I was able to buy them online. :)
I used Sally Hansen's limited edition nail polish in mint sorbet and coated my middle fingers with a sheer green flake/glitter type color on my ring fingers. A lot of people complimented me on this due mainly because they liked the color, and many of them were shocked when they found out it was a drugstore product. :) I love getting great looks for less.