I will have had my iPhone 6 for 2 full years this coming May. That is longer than just about any phone I've had in the last 5. In fact, the phone I had for 2+ years before this one was my Droid Incredible 2, which I clung to until it finally gave up the ghost.
My next phone is going to be a Galaxy. Though I love my iPhone I don't see any innovation from Apple anymore. With the removal of the headphone jack and the addition of the stupid dongles, I don't see any future with iOS. So in May, I'll be onto the next phone. Though I have my pick of Android phones, I'm going to stick to a Samsung phones due to 1. Samsung Pay, 2. VR capabilities and 3. plenty of support and accessories.
I'm not sure if I'm going to be getting an S8, however. I'm sort of fond of the touch button on the front (thanks, iPhone) and definitely not fond of the price of an unlocked phone. My thoughts have always been to stick to Last Year's Model, which I've found to be easy and ethical these last couple of years. The last time I went to Best Buy, I picked up an S7 for fun and was blown away by how good that phone looks and feels. It's really slick -- curves, glass, and plastic in all the right places. I fell in love immediately.
The Verge has a leaked image of the S8 and though it's probably going to be a great phone, I can't say I'm in love with the bezel-less screen and lack of home button. Still, it's probably going to be the best phone released this year and I'm looking forward to getting my hands on a real handset to see for myself.