The ratio that is suitable for your object. We don't know what you want to emphasize on. Try for yourself a bit (16:9 could be an idea) and see how it comes out. Main question: what do you want to show? Where is your main object? But first, straighten up to remove the tilt.wat ratio should i crop it?
Please post a new version of the picture and keep the former one. Otherwise other people cannot see what was changed and how it improved.while i'm walking with my friend, i turned around and find the outline structure is kinda nice so i snap it using my friend's digicam. the weather is nice and warm.