I take second place to no one when beating on AT&T for poor network performance and crummy customer service. But now and then the latest incarnation of Ma Bell does something right, and its implementation of Apple's new iPhone 4S deserves an "attaboy."\n\tHowever, if you are shopping for a new smartphone, the best advice I can give you is to think seriously about how you'll use the phone. If what you really care about is raw download speed and lighting fast Web browsing, an iPhone is the wrong choice. Not because it's inherently a slow poke, but because Apple has not yet built a phone that supports true 4G service, or its most popular flavor known as LTE.\n\tAs I mentioned last week, Verizon's LTE service blows away the competition on data downloads, and if that's what you care about the most, buy an Android (the Samsung Galaxy II is a good choice) and sign up with Verizon.\n\tBut if you're a die-hard iPhone fan you've got to do a bit more thinking before you upgrade. And again, if download and browsing speeds are your priority, AT&T's version of the iPhone 4S is the winner, according to Metrico Wireless, an independent testing firm. (That was also true of earlier versions of the iPhone, Metrico reported earlier in the year.)\n\tMetrico tested the 4S on the all three networks that support it: AT&T, Sprint and Verizon. The company performed more than 21,000 Web page downloads, 8,000 data download and upload tests, and made about 6,000 voice calls.\n\tOn the download front of the wireless war, there was no contest: AT&T's version averaged 3.2 Mbps, compared to 2.3 Mbps for Verizon and a pokey 1.7 Mbps for Sprint. Interestingly, although the iPhone 4S tested much faster than the older iPhone 4 on AT&T's and Sprint's networks, the difference between the two phones on Verizon's network was reversed, with the iPhone 4 testing a bit faster on average. That's not to say that Verizon customers shouldn't upgrade to the 4S -- the new phone is superior in many ways -- it just won't be faster on that network.\n\tWhen it comes to Web browsing, which I think is more important than download speeds for most of us, AT&T was twice fast as Verizon, with mean page load times of 1.29 seconds and 2.60 seconds, respectively.\n\tI did find one aspect of the results surprising. While Verizon and Sprint were rated better on the quality of its voice service (dropped calls and clarity), the gap between them and AT&T was not nearly as large as I would have expected. That difference may well have to do with geography. AT&T's voice service is truly awful in some areas, particularly San Francisco, New York City and Boston, but not nearly so bad in others.\n\tAs always, I think the best measure of voice quality is not a test by a company like Metrico, but the real experience you and your friends have in the places you'll actually use your smartphone for calling.