I use the CND Colour & Effects range. I think they are very reasonably priced and are also very quick drying. The colours used alone are really nice and the effects means you get a whole addition range of options.
I've tried all sorts of polishes over time wanting to stock one brand and ended up with OPI.. Fantastic colour ranges, always bringing out new on trend colours and clients love it and the brand itself speaks on its own... I agree with other posts buy them on vat free days to get the most for your money, i do the same!