I don't use a top coat. I use Londontown nail polish "kur" or "lakur" (the type, NOT the color - it comes in 98 colors - check amazon). My nails *never* chip and the polish is SO durable it lasts for a couple weeks... IF you leave it that long - I don't. Best quality nail polish I've ever used. It shines beautifully and stays shiny, so no need for a top coat. Oh, BTW, it's $16 to $20 but SO worth it.
ETERNITY: your choice... smoking or non smoking!