I have a m7060 12 speed cab pretty close to the m4 and I really enjoy it and I use it for pretty much everything from running square baler, 10’ bush hog, 9’ krone disk mower, food plots you name it. I really wanted a 75c but the price got crazy on them and i have not heard very good things about them or the 75A.
For the OP the 7060 is a better working tractor but the M4 is "deluxe", think the 7060 gets 2-3 more hp to the PTO, if I was to buy again at the 74.9hp range I'd probably look for a 7060.
I have the M4-071 and I love it, but I wish I would have gone to an M5. I run a 9'6" disc on a caddy and it does about 4-4.5 mph on flat ground but if there's any incline I have to slow down significantly even in fairly thin growth, since most of my fields are rolling it slows me down a lot. If I had flat fields it probably wouldn't make a difference. I road it a lot and it will cruise at the governed speed ~25mph until it hits a hill and then I have to shift down even if just the bare tractor. I have a Massey 1840 I bale with and it doesn't notice it's back there at baling speeds uphill or not as fast as I can feed it.
I don't know anyone with a NH 75 but my neighbor got a Deere 5075e. The differences between those to in my mind strongly favor the M4 for haying. Wheel size on the M4 is significantly larger which gives a smoother ride in the fields. I've also helped pull him out of a few mud holes which I was able to drive through. M4 also turns better when stacking bales etc. I like the clutch on the Deere better though, easier to use like a real clutch as opposed to the M4 hydro. Like the Deere's fuel cap location better than the M4 as well.
I'm just over 400 hrs on mine, aside from a hydro fitting that came loose and started leaking at my 3rd function valve I've had zero issues. I added window defrost, rear window wiper, 3pt rear remote, and 3rd function all of which had significant lead times when I bought it so I took delivery of the bare tractor then took it back about 4 months later to have them add everything. The M4 is my first cabbed tractor and 75hp, I'd absolutely buy it again...but like I said I'd probably go with the M5 if I was doing it over.