I had an s4 really liked it but I made the switch to apple with the 6+ and will not look back. It's perfect for everything I use it for which includes Netflix facebook and Internet surfing. Also I like how I can unlock the phone with my finger
I've never been an iPhone fan, and I think Samsung isn't great. I like Android, but, Samsung has so much bloatware. Bloatware has been a problem since the S4, and they made it worse by removing SD card function. I'm waiting for another big dog on the Android platform to make another purchase.
I myself use an iPhone 6 (after upgrading from my first iPhone, a 5s). If you own other Apple stuff (I.e. Macbook, iMac, Mac Mini, Apple TV, or iPad) then get an iPhone. If you don't own other Apple stuff, then I still think you should get an iPhone.
There's waaaay more Malware for droid, and while both droid and iOS devices pretty much have an expiration date, iOS based devices generally last longer (both in hardware and software). The apps for iOS are just plain better. There are better apps available on the app store from more publishers and apps tend to run better for iOS. Also, Apple uses Samsung as one of their main suppliers for their flash storage AND screens which I like (I use and love Samsung's SSDs, monitors, and TVs) except Apple helps design it exclusively to work with their software and other hardware components. Apple is also in talks with Intel to make processors for their next iPhone iteration (theoretically the "iPhone 7") which would give an even better boost to both performance and value.
I also own a Droid based Nexus 7 tablet. It's much older than my iPhone 6, and I'm glad I have it, but that's a fun toy I love to F with. My iPhone is an essential tool that I rely on.
I bought the iPhone 6+ back in April, thinking that I would return it within the 14 day window. Now I don't know how I ever existed with a smaller screen! I've never had any other phone; I'm an Apple addict. However, the 6+ is a marvelous little machine. I can take it on trips and not miss my iPad or MacBook Air.