The most beautiful livery for all times is BA's World Image livery which still is very present. Combining magnificent planes and worldwide, cosmopolitan art is just unbeatable.
But Virgins' silver machines are bautiful too, although they all have the same tails...
Ugly liveries? American Airlines, Air India, Olympic Airways,..., and ALL those similar looking stinky white fuselages plus little little colored logos (if they could, they would fly their planes without any marks) on the tail, as many airlines fly today: Lufthansa (look as boring as government planes), Air France, Sabena, Swissair, Qantas, and many more.
More ideas like BA's or Virgin's needed in that industry!
Me & You & a Plane Named Blue...