Kenworth, Freightliner, Peterbuilt, Mack, Volvo?

Big rigs are cool trucks. I have always been a fan of the 18 wheelers. Especially ones that are very well taken of and have nice paint jobs and trim. But what about performance? Which big rig is the most dependable/durable? KW? Freightliner? Any truckers or former truckers who have an opinion? What about Western Star?