My S5 does everything I need, and quite well. Under 5.1.1, it's still peppy, the camera is fine for what I use it for, and that it gives me full access to the battery and storage while every other maker has gone the other way makes me want to stay with it. However you feel about Samsung, Android fans have a ton of choices now (perhaps too many?) and carriers (well, T-Mobile anyway) will let you bring in and activate any phone you can still stick a SIM in for a reasonable price. I see no reason to upgrade or switch; Touchwiz falis to give me nausea. You couldn't give me an Apple phone, and the S7 is probably the end of the line for Samsung. Seriously, how much more can makers stuff into these devices?
Take a moment and count the number of times the word "hate" comes up in this thread. Makes me wonder about the effect that the phenomenon of smartphones has had on our psyches.