By Louis Ramirez, dealnews senior feature writer For the first time ever, three mobile carriers will offer Apple's newest smartphone, the iPhone 4S, when it debuts on October 14. But while the phone may be the same across all carriers, the plans are not. So we stacked them side-by-side to find out which carrier offers the best iPhone data plan. Least Expensive Cell Phone Packages Verizon Wireless Sprint AT&T Least-expensive plan $30/mo for 2GB (plus $39.99 for 450 minutes) $69.99/mo + $10 for unlimited data (with 450 minutes) $15/mo for 200MB (plus $39.99 for 450 minutes) Top-of-the line plan $80/mo for 10GB (plus $69.99 for unlimited voice) $99.99/mo + $10 for unlimited data (with unlimited voice) $45/mo for 4GB (with tethering; plus $69.99 for unlimited voice) Note: Prices current as of October 2011. All prices are subject to change. Three Choices, One Winner Out of the three major carriers to offer the iPhone 4S, Sprint is the only provider to offer true unlimited data. They've even confirmed that both the iPhone 4S and the iPhone 4 will qualify for this plan. That's something Verizon and AT&T no longer offer to their customers. So, if you're a heavy data user who's looking to save money, Sprint is the hands-down winner. And that's good news for Sprint, which has been betting big on the new iPhone, hoping it can reverse some of its recent subscriber losses. However, with Sprint paying the largest subsidies out of the three carriers for each phone, some people are worried about how long the unlimited plan can last. On the other hand, AT&T, which carried the original iPhone since 2007, now finds itself in an awkward situation. Not only must it continue to compete against Verizon, but it must now also do battle with Sprint. To lure subscribers to its camp AT&T is relying on something called HSPA+. AT&T claims its HSPA+ network is four times faster than other 3G networks. And while that may be true in ideal conditions, it's worth remembering that HSPA+ isn't available in every market yet. Another potential benefit for AT&T is that it will be the only provider to offer the free iPhone 3GS, since the 3GS is a GSM phone only and both Verizon and Sprint use CDMA technology. How Much Data Will You Need? At $15 per month, AT&T offers the least-expensive data plan. And while most people will scoff at the thought of a measly 200MB of data, there are users who can take advantage of that budget plan. The trick is to monitor how much data you use. (AT&T offers a data calculator for that purpose.) AT&T has also added some guidelines, noting that 200MB is enough for: 1,000 email messages (without attachments), 150 that do have attachments, 400 Web page views, posting 50 photos on Facebook, and watching 20 minutes of video from sites like YouTube or Hulu. Our advice, if you're a heavy app user, remember to factor in app updates into your total usage — especially since many of them can be larger than 5MB. Also, keep in mind that an app like Rage HD (a 782MB download) would set you over instantly. Verizon Will Lean Heavily on its Expansive Network Like AT&T, Verizon no longer offers an unlimited data plan, yet it charges nearly as much as Sprint for its basic plan. (It goes way over when it comes to premium data.) So, to combat the price discrepancies, Verizon will tout its network's quality — which has earned them the largest number of mobile subscribers in the U.S. — as a major selling point. Additionally, they will market their iPhone 4S as a world phone, something they couldn't do with the previous iPhone 4, which was CDMA-only. However, it's still unclear whether the iPhone 4's SIM card will be locked to overseas roaming partners or if users will be free to pop in their own SIM card as they travel. The latter would be a huge perk (albeit an unlikely one coming from Verizon) for budget-conscious travelers. The Bottom Line: Unlimited Data May Win Over Many Users Ultimately, if you hate the thought of having to track your data usage, it's impossible to beat Sprint's unlimited offerings; even with its $10/month smartphone surcharge, it lets you download and stream without limitations or concerns about going over. If you just want the least-expensive plan possible (and a free iPhone 3GS), AT&T's plans might work out for you (if you don't mind those dropped calls). And Verizon fans, unfortunately, will have to pay close to Sprint's fees, or more, without the luxury of "all you can eat" data. iPhone users, will you switch to Sprint for the unlimited data plan? An avid gadget lover, Louis Ramirez has covered technology for Gizmodo, CNET, Laptop, and various other publications. Follow him on Twitter at @LouisRamirez. You can also sign up for an email alert for all dealnews features.