Your question needs some context. It all depends on your system and your expectations. If you just want to spend $129 on your digital front end (in other words, the cost of the Airport Express), then I think the AE is the best thing I've found. There are a few very inexpensive USB options, but I haven't tried them. As you move up in price, then you'll need to add a DAC to the AE to try to compete with a USB DAC or stand alone CD player. After trying both, I decided to go with a USB DAC instead of the AE/DAC on my main system and I still have AE's with no DAC connected on my secondary systems.
