Free online music service Pandora has amassed an impressive 20 million users in its three years of existence, according to (citing !).

Back in July, I gushed in an article entitled , noting the killer combination of attributes included the fact that it’s easy, powerful, addictive, and info rich:

This is huge because for something like music – a “product” that’s available in so many places and that will be deployed as background entertainment as I do my online media cultist activities – it has to be super easy and super quick. I’m looking for great music, quickly and easily, and Pandora delivers on that straight off. […]

Pandora confirms yet again that music and the web are made for one another. Music is more popular than ever, of course; it’s the industry that’s getting revolutionized as people are demanding and getting more of what they want when they want it.

I still believe all the things I wrote back in July… but I must admit I haven’t used Pandora in months. The reason? Sirius satellite radio. Maybe it’s unfair to compare a subscription service with a paid one (and of course they’re different in many ways) but I’ve been amazed with the number of ways in which satellite radio has filled multiple grooves and rivulets of my life.

Of course I listen a lot while driving, but the online component is of even greater impact to my life, probably because I’m online such a great percentage of my waking hours anyway!

It hasn’t been all sunshine and roses with Sirius either, I must admit. Back in March, I wrote a piece called While the merger hasn’t been a disaster, it’s affected my life in a small but significant way: I had become addicted to the Boombox station, replete with “break beats and electro rock.” I had never been a big electronic music person, but this station really had an impact on my listening habits.

With the new lineup coming out of the merger, Boombox was canceled. The Sirius website that the Alt Nation station is an acceptable alternative, but don’t believe the hype; it simply ain’t true. However, as a small note of redemption, the excellent Backspin (old school hip hop) station is being brought back from the dead.

So which is better, Pandora or Sirius-XM? Obviously it depends on your tastes and listening habits and budget. For online listening, both are great in different ways. Perhaps the best part about Satellite radio is that there’s great variety that I don’t have to program myself. But I might speculate that people who are a little bit younger than me will prefer the multiple programming and music recommendation options that a Pandora will give you… for free!