What would make me prefer one over the other, without knowing anything about the context or the concept you are trying to communicate? I don't mean to be harsh, but there is nothing in either photo that suggests the point of them.
As Jens pointed out, "the vertical shows the whole scene". But, at the same time, the horizontal shows the heather (?), rock, remains of a rock wall, moss and lichen quite well without the unnecessary foreground and sky, so perhaps this is the better version.
And to title your post "Iceland visit" and use the term "golden circle" puts images of geysirs, the Althing and rift valleys "dancing in my head", so I'm a little let down by the images, although the rock is quite volcanic-looking, and they are both technically well-made. Perhaps the wall has historical significance?