Argentina is so huge that either an internal flight or an overnight bus is the most practical way to get around. Long distance bus providers offer some of the most luxurious and comfortable busses in the world. Taking an intercity bus is like flying. Logically, the higher the category you book the better the service and comfort will be. The most comfy but still affordable option is the cama suite (this is equivalent to flying business class). There will be food & beverages served by a steward/stewardess and you get entertained with a video and audio program. There are many other comfort classes so there's something for every budget. An overview and description of the comfort classes can be found here.