Looks nice, a bit empty in the sky although you could try filling it up with some larger mountains/birds.
The grass also looks to uniform as if with just cloned, grass varies in different sizes and colors along with dead patches so you can keep that in mind
Pretty good. I would maybe add some clouds on the sky.
Looks awesome!! Looks like a game thumbnail!! 
For what you are going to use it for it seems fine, I would add clouds to fill up the empty blue in the sky. The other thing I want to address is that there is too much bloom especially the part where the terrain meets the sky, other than that I’d say it’s good.
There’s a good use of negative space but I can definitely tell that its the same rig duplicated 3 times.
add an beard or something to one of them so it doesnt look the same, l
I like it, as a military geek i enjoy the small details and the HDMIS (background) and the blur effect in the background. I like it and don’t forget the lighting which is clean.