I've tried both MakeItMine and FakeCarrier and they both look a little off to me. The letter spacing on the official AT&T logo is closer together and the typeface may be smaller, I think. Plus you've got that ugly FakeCarrier app taking up space on your home screen.
Some comparison screenshots. Sorry, I don't have Photoshop and ImageReady installed on this computer so I can't do those animations TheSpaz is famous for, but they are helpful.
Original AT&T:
FakeCarrier AT&T (MakeItMine looks identical to this):
FakeCarrier AT&T but lowercase, which I personally think looks better:
I just discovered that if you enter "ATT" as the logo in either FakeCarrier or MakeItMine, it is replaced with "AT&T" on the iPhone's status bar, and looks much more like the real thing.