Nougat.

MM /usually/ is OK for me, but sometimes it just slows down and stops. I feel like my old moto g3 (before it bit the dust) on a SD410 almost ran better more of the time.

I find that my Marshmallow experience on my g⁴ plus is a bit smoother overall than my marshmallow experience on my g³. I don't use adoptable storage on either so that tends to keep things smoother and snappier.
I think nougat should be fine for the g⁴.
 
I find that my Marshmallow experience on my g⁴ plus is a bit smoother overall than my marshmallow experience on my g³. I don't use adoptable storage on either so that tends to keep things smoother and snappier.
I think nougat should be fine for the g⁴.

I have adoptable storage cause I got a 16gb model cause im quite good at breaking phones, but I'm not sure it's adoptable storage.
 
I had an unlocked 2014 X Before my G4 Plus finally arrived (16 days) The battery was dying on my X I did a factory reset to see if that would help. The G is noticeably smoother to me than the X was.
I think it may be the ram because with a few pages open on Chrome on the X and scrolling became quite jerky the G is very smooth.
When I bought the G I couldn't justify another flagship for reading the web, Strava and G-mail.
But it seems to out perform the X.
Never used NFC, miss the compass a little, but the camera and battery make up for that!

Miss leather back too.