As Apple has already launched its large-screen iPhone 6 and iPhone 6 Plus smartphones that both come with a range of upgraded features, it remains a question, especially among iPhone 5S users, whether or not they should leave their smaller-sized handsets for a bigger one.

Comparing the iPhone 5S with the iPhone 6 in terms of the handsets' design, the latter is slimmer and a bit heavier, and comes with an impressive 4.7-inch screen which is larger than the 4-inch screen of the 5S. 

The iPhone 6 also includes an anodized aluminum back panel along with a shiny, stainless steel Apple logo. With its curved edges, users can have an easier time gripping and holding the new smartphone compared to its predecessors. Nonetheless, with a full metal body, the iPhone 5S has still received praises for being remarkably tough and looking impressive at the same time.

In terms of performance, the iPhone 6 comes with the latest 64-bit A8 chips that can generate 25 percent faster performance for CPU and graphics compared to the iPhone 5S' A7 chip. A slight difference when it comes to battery life has been reported. The iPhone 5S had been found to last up to 14 hours and 31 minutes in a non-stop video playback testing, thanks to its 1,560 mAh battery; while its successor is being powered by a larger 1,810 mAh battery.

Storage options for the iPhone 6 have also been impressive as users can choose from the 16 GB, 64 GB, and 128 GB variants. For the iPhone 5S, customers can only avail of the 16 GB and 32 GB models since Apple had already stopped selling the 64 GB version. Both the iPhone 6 and iPhone 5S do not support microSD cards.

Similarly, both phones have 8-megapixel rear cameras and True Tone flash. However, a phase-detect autofocus has been added to the iPhone 6 that will enable users to focus quickly on their subjects.

Apple has also addressed the issues brought on by a shaky hand when taking photos as the company has incorporated digital image stabilization onto their latest smartphone.

Nevertheless, while such differences have been pointed out, the iPhone 6 and iPhone 5S also share similar features, including the built-in TouchID sensor, Siri's voice control, compatibility with the Apple watch, and support for the iOS 8.