I currently use an iPhone 6, but only because it's supplied through work and I only pay $20 a month to rent the phone and unlimited data through AT&T.
Before that I had an LG G4 through Sprint, but I don't see any good reason to pay for two plans, and since my Sprint plan was more expensive I cancelled it. I still have the phone though, so if I get a different job I won't have to get a new phone again.
Before that I had an iPhone 5s (my first iPhone; I had a Droid and Razr Maxx before that), which was alright, but I didn't like how locked-down it was compared to most Android phones (in terms of software and hardware). I know you can jailbreak, but on Android I don't have to, so I'll stick to Android.
As for the iPhone 7, there's no way in hell I'd even consider getting it. The pursuit of thin-ness is completely ridiculous at this point. Phones are already too thin. I have had to buy a case for every phone I've had after my Droid, not because of build quality (I'm pretty protective with electronics), but because they're just impossible for me to hold onto otherwise. On top of that, taking out the 3.5mm jack takes away from features, without adding anything worthwhile. I already have bluetooth in my current phone, computer, etc. If I wanted to use bluetooth earbuds then I would, but I don't want to have to replace my Klipsch R6 and Bose Soundsport, and I don't want to have to buy an adapter because it already works how it is. Why would I pay more money to make something work when it already works with what I have?