iPhone 6s and 6s Plus: Which Carrier Should You Pick?

The iPhone 6s and iPhone 6s Plus are finally here, and Apple fans everywhere are getting ready to spend their hard-earned dollars to get the devices in store starting Sept. 25. Apple's iPhone Upgrade program lets you buy your device directly from the company and upgrade to a new model every year. But even if you go that route you'll still have to pick a service provider. Whether you're thinking of sticking with your carrier, or picking a new provider for your upcoming iPhone, you have many factors to consider.

While the cost of the hardware itself will not vary by much across the Big Four (although T-Mobile has a great deal), differences in plan pricing, network performance, trade-in deals and bonus offers will impact your decision. We've analyzed the pros and cons of each major wireless carrier to help make that choice easier.

MORE: iPhone 6s and 6s Plus Reviewed

For our comparison, we calculated prices for getting an iPhone 6s (16GB) on an individual line with 2GB or 3GB of data across all four carriers. We also looked at the very cheapest option for each provider, taking into account all the deals that are available.

Verizon: Best Performance and Best for iPhone Trade-Ins

This year, Verizon is offering a trade-in deal from Sept. 12 to Oct. 15 that gives you $100 for an iPhone 4/4s, $200 for an iPhone 5/5c, $300 for an iPhone 5s, $350 for an iPhone 6 and $400 for an iPhone 6 Plus (in good working condition) when buying a new iPhone. That's significant savings, and could even halve the price of the new iPhone 6s if you turn in an iPhone 6 or 6 Plus.

If you bring an iPhone 6 Plus to trade in, Verizon's overall two-year cost ($1,850) for the phone on a 3GB plan is a steal. You'll also be hard pressed to find another place that offers $100 for your iPhone 4. Plus, if you do it in a store (as opposed to online), you can immediately apply your trade-in credit as a deposit to cut down on your monthly fee.

Out of all four major carriers, Verizon also has the best coverage and speed, based on our network performance tests. The company also did well on our cellphone carrier tech support showdown this year, meaning you'll get good assistance when you need help.

T-Mobile: Best Overall Value

Thanks to the company's limited-time $125 discount on the new iPhones, T-Mobile is offering a low $20 monthly fee that you'll pay for only 18 months.  Better yet, if you trade in an iPhone 6, Galaxy S6, S6 Edge, S6 Edge Plus or Note 5, you can get the iPhone 6s (16GB) for just $5 a month. Putting up an iPhone 5s, Galaxy S5 or Note 4 lets you get the iPhone 6s for $10 a month, and almost any other phone traded in brings the monthly installment to $15. There's no word yet on when this promotion will end. You'll need to fork over an extra $164 at the end of the 18 months to hang on to your iPhone 6s, but if you intend to trade it in by the time the next iPhone comes out, you won't need to pay extra.

The "Uncarrier" bakes a heaping helping of goodies into each of its Simple Choice lines that will appeal to an array of shoppers. Free international data roaming lets frequent travelers roam free without worrying about racking up fees, while free music streaming means music lovers can stream tunes on supported apps without that bandwidth taking from their monthly allowances. T-Mobile's Data Stash gives each new subscriber (on a 3GB and higher plan) a bucket of 10GB to use over a year, and any unused bytes are stored in the Stash for up to a year.

MORE: Best All-Around Phone Carrier

Calls and texts to Canada and Mexico are considered domestic transmissions on T-Mobile, meaning those with friends and family in those regions will see big savings on their monthly bills. The Uncarrier also announced a new Lifetime Coverage Guarantee program that refunds what you've paid in the first month if you're not satisfied with your coverage. If you have problems after your first month of service, the company will unlock your phone at no charge so you can jump to another carrier, and refund up to a full month of your service.

T-Mobile landed in second place on our carrier speed tests, thanks to its zippy 4G LTE network. And since the new iPhone supports the Band 12 spectrum of radio waves, you'll be able to access T-Mobile's Extended Range LTE, which is supposed to offer better coverage and perform four times better in buildings than before.

AT&T: Best for Paying Off Your Handset Fast

AT&T offers several installment-payment options to let you pay for your device in 20, 24 or 30 months through its Next program. You can also make a down payment up front to get smaller monthly installments and pay off your iPhone faster. For instance, on Next 12 (the 12 refers to the number of months after which you can upgrade), you'll make 20 payments of $32.50. But if you put down a $195 deposit, the monthly fee drops to $16.25.

You'll own your phone at the end of the payments, so you won't have to turn it back in, and you can upgrade to any other brand of smartphone. Those who buy any iPhone on AT&T can also get an iPad mini 2 for $99 (requires two-year contract on iPad mini).

If you have an old iPhone, AT&T will give you up to a $300 buyback credit for an iPhone 5s and up to $200 for iPhone 4/4s or iPhone 5/5c in good condition. The credit received will be in the form of a card and can be applied to your bill, or purchase of a device or accessory (in-store).

AT&T came in third in our network performance tests, but it led the pack in customer service, topping our first annual Carrier Support Showdown. The carrier also lets you roll over unused data each payment cycle, so that your leftover bytes can be added to your allowance next month. (Note that AT&T only gives you the unused data portion from the previous month; by contrast T-Mobile's Data Stash lets you accumulate unused data over a 12-month rolling period.)

Sprint: Best Trade-in Deal

The only provider to zero in on iPhones and provide an Apple-specific lease program, Sprint lets shoppers get the iPhone 6s for $22 a month (for 22 months), and upgrade to the new flagship every year with its iPhone Forever deal. The deal gets better if you trade in a smartphone in good working condition: you'll pay only $15 per month for the iPhone 6s under that option.

Over two years, that works out to just $360, a fraction of the $650 full price. The caveat, though, is that you don't technically own your phone. If you wish to leave Sprint, you'll have to pay off the remaining $290 to keep the iPhone.

While this low price might be tempting, those who need speedy data transfers should beware Sprint's sluggish 4G network. In our performance tests across six major U.S. cities, Sprint came in last of all the Big Four carriers. However, thanks to the new iPhone's support of carrier aggregation (LTE Advanced), Sprint's performance should improve, and its current Spark network is fast where available.

Prepaid Options

Apple has also made its new phones available through discount carriers, including Cricket, Boost Mobile and, soon, Virgin Mobile. You'll have to buy your iPhone outright, but you won't be tied to any contract and you might be able to take advantage of the lower prepaid rates these carriers charge.

Cricket offers the widest selection of new iPhones, with both 16GB and 64GB versions of the iPhone 6s and 6s available. The 16GB iPhone 6s costs $649.99 with activation. Add another $100 if you want to buy the 64GB model. That's also the same price as the 16GB iPhone 6s Plus, while the 64GB version of the Plus costs $849.99.

MORE: Who Has the Best Prepaid Cell Phone Plans?

Cricket plans start at $40 a month for 2.5GB of data. You can knock $5 off your monthly bill by enrolling in the carrier's autopay program. If you make a lot of international calls and texts particularly to Mexico and Canada, you'll want to consider Cricket's $50 and $60 monthly plans, which also increase your data allotment to 5GB and 10GB, respectively.

Bargain hunters, though, may want to look at Boost Mobile and Virgin, which are offering the iPhone 6s at a lower cost. Boost is selling the 16GB iPhone 6s for $549.99 -- $100 less than what Cricket is charging. The 16GB model appears to be the only configuration available from Boost at this time. Virgin, too, sells the 16GB iPhone 6s for $549.99, but you'll have to wait until Oct. 5 to buy it from that carrier.

Boost currently offers a 2GB, $30 a month plan through the end of September that requires you to enroll in autopay. Otherwise, the carrier charges $35 a month for 1GB of data, with plans scaling up to 10GB. Likewise, Virgin's plans start at $35 for 1GB of data.

Bottom Line

The best iPhone 6s and 6s Plus deal at launch appears to be with T-Mobile. Thanks to a generous $125 discount, T-Mobile's cost for the iPhone over two years (with trade-in) is the lowest of the lot. On top of that, the carrier throws in a ton of goodies for frequent travelers and music lovers, and has a zippy network in most major cities. Sprint offers the lowest price of all through its trade-in deal, but its network isn't as strong right now.

If you have an iPhone to trade in, Verizon is an excellent option, giving you up to $400 in credit towards your purchase. The carrier's speedy, far-reaching network will also serve you well in most of America.

Cherlynn Low

Cherlynn is Deputy Editor, Reviews at Engadget and also leads the site's Google reporting. She graduated with a Master’s in Journalism from Columbia University before joining Tom's Guide and its sister site LaptopMag as a staff writer, where she covered wearables, cameras, laptops, computers and smartphones, among many other subjects.