The catch to answer this question is definition of “Best” is not constant 
Processor: There are phones like Samsung Galaxy Note 4 using an eight core processor Exynos 7 Octa making it one of the best processors in the smartphones (one of the best, because there are other similar processors like Snapdragon 810)
Camera: Phones like iPhone 6 Plus and Nokia Lumia 1020 use larger camera sensors that are able to take sharp images (even in low ight) making them phones with best cameras. On the other hand phones like Samsung zoom provide 10x optical zoom to take images of distant objects making it best zoom.
Operating System: There are various operating systems but iPhone’s ISO is most reliable in terms of security and operation making it better that Android that hangs occasionally.
Apps: IOS and Android based phones are best when it comes to install apps whereas OS like Firefox is struggling to provide more apps to users.
Battery: Smartphones struggle to stay up in lack of powerful batteries but with a 5300 mAH battery Philips W6610 is the best
Sound: I found HTC is the best when it comes to listening music
Security: Blackberry and iPhones are best again
Value for money: Many china based companies are providing more powerful processors, more RAM and more storage than established brands like Samsung and iPhone so users looking for value for money they find Huawei ascend mate 7 series and Xiaomi Mi4 best.
Choose your best
