What makes a good t-shirt?

I don't know if I have figured out the formula for a good t-shirt. I know it when I see and wear one but why is it good? Obviously there is a component of fit and feel. The fabric has to hang well and caress the skin. But what of the design? I think a balance exists within the design. It has to complement the shirt as much as the shirt complements the design. The colors have to be right. The texture must harmonize.
I think most people would agree that a worn in t-shirt "feels" better than a new one. There may be a component of current fashion in the statement but, in general, worn cloths feel better than new clothes. There may be exceptions. Jeans, however, are the prime example of a material that conforms to the wearer. The more you wear a pair, the more comfortable they become.
I recently came across an interview in GQ magazine (March 08, I think) where a well known hair stylist stated that he never washed his jeans, just threw them in the ocean and let them dry. Perhaps an extreme. To that end I researched reasonably easy techniques to "age" a new t-shirt. There are multiple methods but the one I tried was soaking the shirt in salt and white vinegar for a couple of days then washing and drying it. I got mediocre results. I also tried borax and salt soaks. Again, mediocre results. The shirt came out better than it was but not how I wanted it. Suggestions?