In terms of composition, I think the view coming up Franklin Street is my favourite, largely because you can see it from base to tip. Looking southwest from Washington Street isn't bad, but you can't get as good an unobstructed view from any of the other nearby streets without being right up against the building.
And yeah, the view from Digitas' deck probably isn't the most flattering (especially with a smartphone camera). It's basically the same view as from the eastern corner of Hawley and Franklin Sts but 18 stories up. It just struck me at how close it was; when I was working there up to a few months ago, I couldn't visualise how much it would dominate the view. There are only a few places in Boston where there's another big skyscraper just 50m outside your window.