The M gets the nod if you think HDR10 will matter to you (you probably know this but for me, I don't bother.) Since I have a Roku and the Amazon Fire 4K the smart part of the TV won't matter.
Now I can't guess if the 65 to 70 inch matters so I think it's down to the M65 or the E70. Since my viewing room is known to me the 65 inch would be fin. Nod to the m65 for me.