There is nothing like though choice.
Note 4 advantages,
Stereo recording mics
Droid Turbo advantages,
Better reception vs Note 4)
Nexus 6 advantages,
Fastest of all
Camera vs Turbo, a bit worse vs Note 4
Display vs Turbo, equal vs Note or slightly weaker then the Note 4
Reception vs Note 4
Front facing stereo speakers vs Note 4 especially, and Turbo
On screen buttons, vs Note 4 especially, and vs...