This is one question we often hear from our friends or family members buy an expensive phone like an iPhone or a HTC one M8 etc..
So this is how we at Whackk! try to answer the question.
These new high end flagship phones that are coming out lately are focused more and more on the design, things like processor & ram doesn't matter much (especially with the KitKat and android L update in android).
Basically every phone on the top of the lineup of the manufacturers are great and there are just two ways to decide which phone you want to buy,
1. Software (UI/skin)
2. Design/hardware/feel in the hand
And that's why these manufacturers have spent many hours of research and development to perfect the design and put the best one on the shelf. Every curve,edge,button layout has a reason. The designers make the phone thinner and lighter and push the limits of physics to fit as big a battery, camera lens or speakers as they can into a beautifully designed phone. So when you decide which expensive phone you want to buy you'll really appreciate these details of all the fine things they considered and really appreciate the design of the phone.
Then come along these case manufacturers that spend sometime to study the design of the phone and create a rubber or plastic case for your phone. Once you snap these covers/case on your phone, the beauty, the design features, the curves, the minor details, the feel of the phone is all lost. BUT you do that to protect your expensive phone right?
Lets get one thing straight. The 'drop test' videos on YouTube of the phones with the covers prove that 'No case (with a few exceptions) actually prevent your phone from getting damaged from any significant height (on your screen especially)' unless you're using an otter box defender. The only protection the case offers is against the direct impact between your phone and whatever surface you drop the phone on.
For example: if it is a metal phone and you drop it on a concrete surface, you prevent the metal on your phone from getting scratched which is great but so do 'Skins'.
These skins can be applied like a screen protector on the back of your phones that are thick enough to protect your phone as well as a thin rubber case would against a drop from the height of your pocket. They also seem to improve the feel in the hand.
Consider the HTC One M8, a tall and large metal phone. The power button on this phone is on the upper side of the phone on the corner. So one has to move his hand towards the top while handling this large phone in one hand and with those smooth rounded edges its just an invitation for a drop.
So you can add a carbon fibre skin to the back of the phone and your problem is solved. It gives your phone a distinct look and also gives it some texture for some grip. Skins for (popular) phones and laptops are easily available online.
The added advantage is that if you are one of those people who love changing your phone too often, all you need to do is rip off that skin and your phone is as good as new (which should be able to fetch you a good selling price)