Two main planets make up the streaming-music universe these days: Pandora and Spotify. I live happily on Pandora, and though I do like the new Spotify iPad app, I don't like it enough to switch planets.\n\tNearly three years ago, Spotify released an iPhone\/iPod touch app to enable its desktop music subscribers to stream music on their iOS devices. With the current version 0.5.0, released May 2, Spotify\u2019s free iOS app is now optimized for the iPad Retina display. (Spotify is also available for Android, Windows Phone, BlackBerry, and Symbian phones.)\n\tSpotify on the iPad makes good use of the larger tablet screen. For example, as you jump back and forth between the app\u2019s Playlists, What\u2019s New, Search, and People sections, the currently playing song shows at the bottom of the screen along with playback controls. This feature isn\u2019t available in Spotify for iPhone or iPod touch.\n\tFeature-wise, Spotify on the iPad is essentially the same as it is on Apple\u2019s smaller mobile devices. On all Apple iOS devices you can stream music to your stereo thanks to the app\u2019s AirPlay support, listen to music curated by Facebook friends and share your playlists with them, wirelessly sync your computer\u2019s music library to Spotify on your iOS device and more.\n\tBut as if often the case with mobile software, Spotify on the iPad lacks some important features from the music service\u2019s desktop apps. It doesn\u2019t support Spotify\u2019s newly emerging ecosystem of apps, for instance. And you can\u2019t drag and drop tracks into playlists, as you can with the desktop Spotify app.\n\tWhen you first install Spotify\u2019s iOS app, you automatically receive a free, 48-hour trial of its premium service. The service removes ads, lets you listen to playlists offline and streams music at the high bitrate of up to 320kbps on your computer.\n\tSpotify\u2019s premium service is $10 monthly (there\u2019s also a $5 monthly unlimited service). Pandora, which also has an iOS app optimized for the iPad, removes ads from its service for just $36 a year. That\u2019s a big reason why I prefer Pandora. Here\u2019s another: By creating \u201cradio stations\u201d based on your favorite artists or songs, Pandora does a far better job than Spotify in helping you discover new tunes you\u2019ll most likely enjoy. And that\u2019s why I live on planet Pandora--with occasional visits to Spotify, of course.