I like it simple, clean and stylized, my personal preference is number 5, with perhaps a little more detail such as in the upper-left screenshot of this page. I think the brightness of number 7 is somewhat off. Six is interesting too and comes close to the colors I prefer, but like it says, I don't like the volcano like edges on the hills.
What I really like about number 2 is that it says, this is it, it's about the game. You get a clear oversight of your troops and options and it's all about the actions you make, not so much about the immersiveness. The gray works well on the red and I'm not opposed to this one either. But, I will fill in the but for me.. I think it belongs more to a pure multi-player competitive game. A game, which I would VERY much like and I hope, if this game is a success, you will consider..
Bare, but highly stylized with a wiff of a past century presented in the colors, well gray, and just all about your strategic decisions against another human being.