Ok, let's be real. OPI is like THE nail polish brand. Everybody knows it's amazing, and everyone knows why. All the colours I've tried have been a really good formula, really opaque (sometimes even in one coat, which is amazing) and some beautiful colours. They don't tend to chip easily, especially with a great top coat.
My absolute favourite go-to colour is Taupe-less Beach, which is part of the Brazil Collection, I think. It reminds me of Lime Crime's Cashmere in nail polish form. It is amazing. Plus it's pretty opaque in one coat. Not completely but you could definitely get away with it if you were in a rush.
The only one colour I have found that I don't like is a beautiful colour, but a crappy formula. It's called You're Such a Budapest and it's a beautiful periwinkle blue/light violet with really subtle shimmer in it. Ugh, it is so gorgeous. The problem I have is that it literally takes at least 3 coats to be opaque/not streaky. I don't have time for that so I never reach for it :(
All in all, this is a fantastic brand with so many amazing colours and pretty consistantly awesome formulas.
Ooove this brand! This has now become.the only brand I use. Two coats of any colour-it doesnt chip easily and isnt like those see through nail polishes that just look downright gross. Love love love
Tips: O coats is always better than one!