What makes music come alive. True, there are exceptions, but practically all of my favourite music has interesting bass lines:

• polyphony from the renaissance and baroque (Clemens non Papa, Dowland, hundreds of other composers)
• the Beatles (my favourites: Hey bulldog, And your bird can sing, I am the walrus)
• Bach (the French suites, or anything else he wrote)

If you're a musician, and you want to sell your music to my ears, pay attention to detail, and most of all, to the bass lines.