As you read this, thousands of users are descending on AT&T stores the world over. They won’t be deterred. They won’t be denied. They’re won’t be bamboozled. They want the latest and the greatest in devices powered by the new Windows Phone 8 operating system. If they’re on Sprint the answer to the question they seek is simple – switch carriers. If they’ve gained their sanity and moved to one of the other smartphone service providers there’s only one important thing they want to know now: how to make the best choice out of the choices available.

Fortunately for them. It’s very simple. You go with where the apps are.

Talk to any reviewer and he’ll tell you that conventional wisdom says that all Windows Phones are the same, software wise. Nothing could be further from the truth, and it’s important that you understand this before you choose your next Windows Phone. I know this because I’m struggling with that same choice right now.

For months now I’ve been vying for a new flagship Windows Phone device. As an HTC HD7 owner I stood by as Nokia joined the Windows Phone fold and delivered the amazing Lumia 900, and the only think I could think about besides how amazing that device looked, was its superior selection of applications. Nokia Drive, Nokia Maps, and Nokia City Lens are one of a kind apps and are unrivaled by HTC and Samsung. Period. Don’t get me wrong, it’s not that HTC’s Flashlight app isn’t useful, it’s that it isn’t an application that changes the fundamental Windows Phone equation. To HTC’s credit their devices also ship with Calculator, and widget area turned app the HTC Hub – for what that’s worth at least.

As if that wasn’t enough Nokia is also playing it smart by providing its users with exclusive third-party applications that can’t be downloaded by phones of any other device maker including PGA Sport, ESPN, Groupon, TIME, Newsweek, AOL, TripDots, PayPal, and Electronic Arts. It’s unclear yet if any of these applications will make their way to other Windows Phone users.

What you’re left with is the realization that the biggest app related choice you will make when either switching to, or upgrading a Windows Phone is right at that very moment you hit the “buy” button.

Now this isn’t all to say that it’s the most important choice you’ll make about choosing a device. As always form factor and included technology is always a big factor. However increasingly the Windows Phone ecosystem is starting to develop a kind of mutation of a problem we first saw manifest inside the free-for-all of the Android ecosystem. Sure, this isn’t a problem that’s anywhere close on the scale to Android operating system skins. It’s fragmentation on a much smaller scale and because it’s so small it’s downright easy for most users to miss.

My point is this, on the day we finally mark the launch of modern Windows Phone devices, running a modern version of Windows Phone – make the right choice. You’ll have to live with it for two years.

Windows Phone App Flow will kick off a three week series on Windows Phone 8 apps starting next week.