She is the biggest star, but then again although she can sell out every stadium I don't see her liive voice keep up with her status as biggest star in US.
Taylor just came out with a single, which is why she's on people's mind and appears to be bigger than she is. Give GaGa till her next lead single and Taylor will be nothing more than a distant memory. But even her current status doesn't touch the heights of GaGa and Rihanna's stardom at their respective peaks so far.