10 billion downloads strong, Apple’s App Store remains the yardstick by which all rivals are measured. Cupertino’s attempts to trademark the phrase ‘app store’ might seem a tad extreme, but the success of its virtual emporium is undoubted. It’s hard to remember a time when the Apple’s download market didn’t exist, even though it’s just two and a half years old.

Every top-end phone around has been influenced by the advent of easy app access, and any Apple rival suggesting it hasn’t had a positive effect on their own handsets is surely not to be taken seriously.

Apple’s Phil Schiller said last week, “The App Store has revolutionised how software is created, distributed, discovered and sold.

“While others try to copy the App Store, it continues to offer developers and customers the most innovative experience on the planet.”

It’s hard to argue with that assertion. Android Market, although around before the App Store, doesn’t offer the same all-round breezy experience as Apple’s version, while the Ovi Store, Windows Marketplace and BlackBerry App World all feel a lot less fun to use. So how can Apple’s key competitors get a look in?

Android Market is surely the number one rival, but it seems Google is quite happy to allow third parties, including Amazon, offer their own app stores on their phones, immediately stopping it being able to match that dizzying 10 billion figure.

While it’s not in Google’s DNA to stop this, this kind of fragmentation is surely a bad thing for Android. The lack of a unified experience is loved by some, but most third-party app stores, like Archos’ AppsLib effort, are nowhere near the level most smartphone and PMP users have come to expect. Hopefully, Google will up its game even more with Honeycomb and bring a more compelling version of Market to its phones.

Windows Phone 7’s app outlet is snazzy, but while apps work well in the context of the OS’s Live Tiles, the experience still isn’t as straightforward as Apple’s. It just doesn’t feel as if add-ons have been put at the front and centre of Microsoft’s mobile OS, and the same goes for BlackBerry. The latter feels too business oriented and doesn’t bring the same pleasure as snaffling the latest cheap goods on the iPhone, iPad or iPod touch.

Of course, it’s all about enticing developers too. Apple’s system has been relaxed after some stringent guidelines were put out last year. But the fact that Apple’s store is vetted gives it the distinct advantage of offering mostly top quality stuff.

Again, this runs against Google’s open philosophy, but being more wary of what goes onto Android Market would certainly drive the levels of quality up. Of course, there’s the argument that Apple is too controlling. But to most users, as long as they can get the apps they want in a swift fashion in an intuitive environment, that is of little concern. For now, the App Store rules supreme. But with tighter controls and a more singular experience, Android and others could easily start to push Cupertino in the add-on stakes.