I don't quite understand the problem people have with green arrow markers. It's a clear visual that helps you to determine which unit (or units) you have selected. When you order your troops to do something you can always deselect (press Enter) them and the arrow markers disappear. Perhaps it's a matter of different play styles. I don't particularly like them, but I don't hate them either, because they are very functional. I'd rather have them them enabled to see which unit I have selected than have them disabled and guessing that I have selected the unit that I had intended to select.