Salami

I'm going to completely disagree with the OP - for me the longer the better. There's little I dislike more than an idea I'm starting to appreciate being snuffed out too early. I'm not saying I like sounds to be repeated and carry on forever, but I do like to be able to really get a feel for what I'm listening to. Six minutes and upwards I think is best because that gives time for experimentation within the idea of the song, or in the case of Bob Dylan type songwriters the opportunity to build up to a climax.

I'll give an example of a song that ought to be a lot longer that is not selected for any particular reason but because I happen to be listening to it:
"Personal Jesus" - Johnny Cash: Johnny Cash is indisputably one of the greatest country artists of all time and his wonderful voice inimitable. The nearest song I can think of which sounds like it is "Whorehouse Blues" by Motorhead, but the point is it's a great idea, well written song but damn it only lasts for three minutes. Perhaps some sort of instrumental section in the middle further exploring the dark aesthetic the song has been producing, even a little guitar solo, but it's over too quickly.