I have used an S7 Edge and an iPhone 6s Plus back to back for months now, so I feel well placed to give my opinion.
The overall winner is unanimously the S7 Edge (that's saved some of you reading further down).
The main reason for this is the software. iOS is riddled with bugs that you wouldn't expect on a cheap android phone, let alone a £650 iPhone.
Software
The S7 Edge has a smoother, faster and far more intuitive user interface. Apps are genuinely running in the background, and not the fake pauses that iOS does. This means you can jump between two things.
iOS is riddled with bugs, from the reminder app to FaceTime. Apps don't crash, which is good, but no effort has been made to fix bugs that have been there for years.
The whole iOS is a dumbed down version of a smartphone. This, coming from someone who has owned an iPhone since the original. It just hasn't moved on. The widgets on the iPhone are comical.
In addition, some basic UI elements have been completely overlooked, like the force touch on the lock screen is at a different sensitivity setting, so you have to press harder than in other places on the phone.
One thing going for iOS is the adoption rate amongst the UK population. Most of my friends and family have iPhones, so iMessage and FaceTime are superior to Google hangouts (crashes regularly) and WhatsApp.
Voice Assistant
Siri is utterly useless, struggling to understand basic commands. Often, Siri is far less sensitive and so it misses words. On the exact same phone, with the same intonation, the Google app voice search picks it up perfectly.
Siri has bugs, many bugs. Example: "Siri, set a reminder for parking at 4:30"
Sometimes it will set a reminder at 4:30. Other times, it simply creates a reminder titled "parking at 4:30".
Another one, you press for Siri, and immediately it says "I didn't get that". Comically sh*T
S Voice is also useless, because it is buried in the phone and doesn't appear to be linked with the apps. However, Google Now is instant and never gets it wrong. One downside, it can't run some apps on the S7 Edge. This is a larger problem with the division between hardware and software.
Display
When I got the 6S Plus, I'd been running the S7 Edge for some months. I turned the 6S on and went to YouTube. I genuinely thought the screen was faulty. It seemed incredibly grainy and washed out. The S7 is over-saturated, but my preference is definitely for the S7.
Camera
The camera on the 6S is okay in good lighting (note, I am not a photographer, just a typical consumer). However, the low light performance is terrible. This is where the S7 Edge steals a march. The rear camera is phenomenal. There isn't another word for it. The speed at which it fires up and snaps is amazing. The front camera, whilst having a great wide field of view, is terrible. It has this weird blurring effect on faces that look very fake.
Battery
The iPhone wins hands down. I can easily last an entire day and then some. Whilst the S7 Edge has fast charging, there isn't a need to do that if the battery lasts until midnight. I never used wireless charging on the S7 and felt no desire to. Tad gimmicky. Also, the 6S can charge very quickly with the iPad charger.
Fingerprint Scanner
iPhone wins hands down. It's not that the actual scanning is quicker, but the accuracy is far far greater on the iPhone. I haven't had a non-recognised press yet! On the S7, these were probably half of the presses - very frustrating. When I actually had them both on, and placed my finger exactly, this is where the S7 won. But that isn't remotely representative. A large part of this may be the fact that fingers are more round (iPhone home button) than rectangular (S7 home button). This seems small, but it actually makes it much more pleasurable to use the iPhone quickly, out of your pocket, adding immensely to the experience.
My preference: The Galaxy S8 when it comes out. Hopefully this will correct the above flaw in the S7. iOS is falling very far behind in being a good UI and I have heard several anecdotal stories of people switching to premium android phones, because they do the same thing for less money. Which is the point, if I pay a premium, I want a premium UI!
The overall winner is unanimously the S7 Edge (that's saved some of you reading further down).
The main reason for this is the software. iOS is riddled with bugs that you wouldn't expect on a cheap android phone, let alone a £650 iPhone.
Software
The S7 Edge has a smoother, faster and far more intuitive user interface. Apps are genuinely running in the background, and not the fake pauses that iOS does. This means you can jump between two things.
iOS is riddled with bugs, from the reminder app to FaceTime. Apps don't crash, which is good, but no effort has been made to fix bugs that have been there for years.
The whole iOS is a dumbed down version of a smartphone. This, coming from someone who has owned an iPhone since the original. It just hasn't moved on. The widgets on the iPhone are comical.
In addition, some basic UI elements have been completely overlooked, like the force touch on the lock screen is at a different sensitivity setting, so you have to press harder than in other places on the phone.
One thing going for iOS is the adoption rate amongst the UK population. Most of my friends and family have iPhones, so iMessage and FaceTime are superior to Google hangouts (crashes regularly) and WhatsApp.
Voice Assistant
Siri is utterly useless, struggling to understand basic commands. Often, Siri is far less sensitive and so it misses words. On the exact same phone, with the same intonation, the Google app voice search picks it up perfectly.
Siri has bugs, many bugs. Example: "Siri, set a reminder for parking at 4:30"
Sometimes it will set a reminder at 4:30. Other times, it simply creates a reminder titled "parking at 4:30".
Another one, you press for Siri, and immediately it says "I didn't get that". Comically sh*T
S Voice is also useless, because it is buried in the phone and doesn't appear to be linked with the apps. However, Google Now is instant and never gets it wrong. One downside, it can't run some apps on the S7 Edge. This is a larger problem with the division between hardware and software.
Display
When I got the 6S Plus, I'd been running the S7 Edge for some months. I turned the 6S on and went to YouTube. I genuinely thought the screen was faulty. It seemed incredibly grainy and washed out. The S7 is over-saturated, but my preference is definitely for the S7.
Camera
The camera on the 6S is okay in good lighting (note, I am not a photographer, just a typical consumer). However, the low light performance is terrible. This is where the S7 Edge steals a march. The rear camera is phenomenal. There isn't another word for it. The speed at which it fires up and snaps is amazing. The front camera, whilst having a great wide field of view, is terrible. It has this weird blurring effect on faces that look very fake.
Battery
The iPhone wins hands down. I can easily last an entire day and then some. Whilst the S7 Edge has fast charging, there isn't a need to do that if the battery lasts until midnight. I never used wireless charging on the S7 and felt no desire to. Tad gimmicky. Also, the 6S can charge very quickly with the iPad charger.
Fingerprint Scanner
iPhone wins hands down. It's not that the actual scanning is quicker, but the accuracy is far far greater on the iPhone. I haven't had a non-recognised press yet! On the S7, these were probably half of the presses - very frustrating. When I actually had them both on, and placed my finger exactly, this is where the S7 won. But that isn't remotely representative. A large part of this may be the fact that fingers are more round (iPhone home button) than rectangular (S7 home button). This seems small, but it actually makes it much more pleasurable to use the iPhone quickly, out of your pocket, adding immensely to the experience.
My preference: The Galaxy S8 when it comes out. Hopefully this will correct the above flaw in the S7. iOS is falling very far behind in being a good UI and I have heard several anecdotal stories of people switching to premium android phones, because they do the same thing for less money. Which is the point, if I pay a premium, I want a premium UI!