Question [Q] What would you get???? Gurus!

Hi all,
There are a lot of super smart users on this site. They can and usually seem
to find solutions to most cell phone issues. My question to you all is:
Currently have the S4, ATT, stock. I will be upgrading later this year.
Which phone would you recommend to me with these uses:
Fast, no lag- No bloat apps- Fast upgrades- Probably won't root.
Use phone for everyday normal usage, not a gamer.
My choices so far:
S5, Z2, New Nexus when released!
Leaning to to a Nexus or possibly a GPE of the above choices.
Any guidance would be helpful.
Thanks, Ken