For the best ecosystem
Look no more beyond the iPhone 5 (or the older models of the company).
It was on Apple's app store where the now iconic, Angry Birds, was first published, appreciated and went on to be replicated across app stores on different mobile OSes.
There's no dearth of free and paid quality apps on the iOS devices when the app store offers 700,000 apps (as of today).
Unlike Android's app store, Apple takes great efforts to curate its app ecosystem, frequently turning away legally dubious, ethically questionable or non-functioning apps from its tightly controlled store.
While yet to be officially launched, we are putting Nokia Lumia 920 & 820 here because of its music store, mix radio and ever growing library of multimedia content that the company keeps adding.
Windows Phone apps hover at about 120,000 apps today, and this would make smartphone buyers value Nokia's music library - 4.5 million DRM free songs - even more.
Also, Nokia's navigation apps like Nokia Drive, Nokia Transit and Nokia city Lens are a definite plus.