I think there's a continuing trend in the motorsport world where clean, flowing liveries are the preferred flavour. I think criteria for a generally well received livery include an identifiable main colour matched by another, or complimented by one or two more. Racing stripes are generally a winner alongside paint jobs that sweep across the car in a clean way. Finally, it is important for sponsors' colours to compliment the car's livery. With all that in mind, I think the '98 Arrows A19, which as already been cited, is a prime example. This in particular begs the questions as to why black F1 cars are generally unpopular.
Purely opinion motivated, there are too many white and red cars abundant. White F1 cars don't look very attractive, but there are some exceptions.
While not entirely white, there's some lovely charm about this livery. Certainly not the best, but I can't see how it is bad.
blue and green should never be seen, but this is one of my favourite F1 liveries that seems to defy all conventions of a 'good' livery. Pastel blue just looks damn good on this car.