I've had 2 nexuses so far, and I must say I'm going to Samsung.
I had the Nexus 4 and now I have Nexus 6 for a year and a half and I'm not very happy with it.
I was a huge fan of Nexus phones, said I would only buy them, hated Apple.
Now I dont think I'll go for a new nexus and even the iPhone looks good after I bought my wife a 6s.
On my N6 the battery life is ATROCIOUS, its become very laggy at times (when the battery falls under 40-50%), the camera is very slow to take pictures and sometimes it freezes when recording, etc.
I suspect some of these issues may be resolved when I do a factory reset, but all in all I'm not very happy with it.
Not to mention that the Nexus letters on the back fell off after a few months.
It just seems a bit too raw and unfinished for me. When I was younger and had more time I didnt mind messing around with phones and custom roms and what not.
Now when I'm older and have a family and demanding job I just want a phone that works as it should with as little input from me as possible (I understand iPhone users

)
I like the S7 edge, but I think I''ll wait for the S8 edge and get that when it comes out.