I love using OPI nail polish, it's abrand I can always trust.
Te colours are amazing and so much variety, and the mixture is not too thin & runny like some of the cheaper brands. I can build layers, or just use a couple. It's also quite hard wearing and stays on until i take it off myself.
Bottles are also easy to grip when your nails are still wet and the brush is easy and doesnt streak.
I love these polishes, my favourite formula by far - they go on really smoothly and I haven't had one that's needed more than two coats. The brush is good too! Lincoln Park After Dark has got to be my favourite colour.
Tips: Make sure you use a base coat otherwise you could stain your nails (especially with the darker colours).