I'll start it off... I think that SQ's 1970's livery was probably the most attractive all-around livery I've seen. The graceful logo to me conveyed a sense of graceful service, the sharper angle of the cheatline "cut" projected a sharp, cutting-edge company, and the navy-blue/yellow color scheme projected a crisp corporate image.
Photo © Lee Cheng
Photo © Marcel Walther
Photo © Bill Blanchard
Photo © George Canciani
Please do not include one-time special promotions, or continue the now dreary new UA livery debate. I would like to know what elements of a livery enthusiasts, airline employees, and passengers consider relevant and/or important.