Our daughter works for Apple. I JUST talked to her about this subject last night. She says the BEST one is from Power Support (iPhone , iPad , iPod & MacBook Accessories | Power Support USA
), and that they go on without bubbles, as well. They aren't cheap
, but she says they are the best AND Apple does not sell them in the stores.
I just ordered one for myself. She says the "hot dog" technique works best: Hold the screen
like a hot dog, lengthwise, and line it up on the button and the camera
dot a the other end, then just drop the sides. I'll tell you how this works out...