What's your current "go to" music service?

First off, I saw there's a "how do you listen to music" thread going on but that seems like it's mostly about gear.

I've been using Google Music since I've switched to Android back in June and I love it. But discovering new music as well as the lack of time to set up cool playlists has becoming an issue for me. I've been checking out Songza which is pretty cool (and free) but it's missing some stuff that I would like, probably because it's free.

So I'm going to invest into some service but want to hear about them from people before. I will probably still use Google Music since most of my library is up there but I just want a "click and forget" music service to go together with that.

So in short: what's your current music service and why?

Cheers.

Edit: Way more responses than I expected. Some really great answers out there and definitely a few services I've haven't heard of before.

I'm loving Rdio but I want to tryout Mog before I decide. But looks like I want to keep Songza at hand as well since I love their "concierge" approach. Similar to 8tracks I guess but way more quality playlists.

Thanks everyone!