Today is iPhone day. Again. iPhone 4S presale order sales started at midnight. For the first time there are three different providers offering service plans for iPhones: old standby AT&T, Verizon and newcomer Sprint, plus there's an unlocked phone that theoretically could hop from network to network. With so many options, which phone to buy? The actual phone costs the same with each carrier, so it's all about the plan. With so many possible combinations of voice, data and texting, things can get kind of confusing. We're here to help.

AT&T

Pros:  The original iPhone service provider hopes to keep customers with reasonable prices. It has the lowest possible price plan: For $54.99 per month you get 450 minutes ($39.99) plus 200 MB of data ($15) and you can opt for pay-as-you-go texting. AT&T does not have any roaming charges in the U.S., unlimited mobile-to mobile-calling anytime and rollover minutes. Because it runs on a GSM network, it's the fastest for data and the only phone that allows for simultaneous talk and data usage. 

Cons: 200MB is tiny amount of data. It's not even a half an hour of streaming music, according to the AT&T data calculator. If you go over it automatically charges $15 for additional 200MB increments. And pay-as-you-go texting sounds like a potential financial mess at $.20 per text ($.30 if it's a picture messages), which means texting "Where R U?" and "C U there" would cost almost as much mailing a first-class letter. Beyond the potential to surprise you with some scary charges, AT&T also doesn't exactly have the best reputation for phone service. "AT&T has a reputation for dropping calls consistently and having more dead zones than other carriers, especially in some metro areas, such as New York and San Francisco," explains GottaBeMobile's K. T. Bradford. AT&T ranks last in customer service, according to J.D. Power and Associates.

Verizon

Pros: Verizon's not as budget friendly as AT&T, but it's less frustrating. It's number one in reliability, according to J.D. Power and Associates. While the data plans aren't the cheapest, Verizon offers the widest range of options, from 2GB to 12 GB per month. Its pay-as-you-go texting is about the same as AT&T: $.20 for text $.25 for picture and vid. 

Cons: Verizon is pricey. It's data overage charges run at $10 for another GB every time you go over. The cheapest option comes in at $69.99 per month--that's $39.99 for 450 minutes and $30 for 2GB of data. And for what you pay, its data runs a bit slower than AT&T's. And, which also means no simultaneous voice and data. Translation: You can't use the Yelp app while on the phone with your sister. 

Sprint

Pros:  Unlimited data. The new kid on the block is trying to lure customers as the only provider with this option. While Sprint charges more for minutes, unlimited data sweetens the deal. It's cheapest offering runs at $79.99 per month: $69.99 for 450 minutes, unlimited texting and another $10 for all the data you could ever want.  

Cons: Unlike AT&T and Verizon, Sprint still requires a text messaging plan--no pay as you go. Also its unlimited data can't take advantage of the speeds that AT&T's data can. And, again, no 3G surfing while talking. 

Unlocked 

Pros: Freedom. There's no contract involved and in theory an unlocked iPhone means users can switch carriers on a whim. 

Cons: It doesn't work quite like that. Technically speaking: "In order to work on a CDMA network, an iPhone 4S has to be activated on a CDMA network at time of purchase (and switching a device even between Sprint and Verizon is harder than one would think)," explains AllThingsD's Ina Fried. Translation: It only works on T-Mobile on its slow poke 2G network. This same principal also messes with the new world-phone feature, which theoretically should work on both GSM and CDMA networks in different countries. "While an iPhone 4S activated on Sprint and Verizon can roam onto GSM networks, such as those used in Europe and parts of Asia, an iPhone activated on AT&T won’t necessarily be able to run on CDMA networks outside of the U.S., such as those in Korea," continues Fried. It also come out later than the other phones, with a November release date. And the actual phone costs a bunch: $649 for the 16GB and $849 for the 64GB.