Depends which application you're talking about. Some of the applications that I know are clearly better on Android:
FourSquare, Layar, Yelp, Twitter for Android, Opera Mini 5.1, Google Maps, Google Earth, EverNote, Facebook (arguable some things better on Android, others on iPhone), GMail, Seesmic. There are apps whose capabilities have no equal on the iPhone, like Dolphin Browser, Google Sky Maps. Heck if you have seen the Tweetdeck for Android beta, it just leaves the iPhone version behind. On Google Earth, Android version, you can now go underwater and explore the ocean floor like a submarine.
Basically, once apps use geolocation, augmented reality, background/Push notifications, contacts sync, OCR or bar code recognition, talk/voice recognition/command, and link sharing, they're better on the Android side. While the Samsung GPS needs to be improved, the GPS capabilities on the Motorola and HTC Androids are just incredible, fast and pinpoint accurate.
Of course, games and some blogging apps like WordPress are better on the iPhone side for now, but for how long.