I would go with the dark green. It adds contrast to the red - opposite on the spectrum. It gives a hint/visual reference of verdigris, blends with the background and forces the brick work to come forward - visually supports the brick facade.
I would repaint the trim - windows, eves, door frame a darker grey/green almost the same colour as the roof - 80-90% - the same. If it is too dark it will create "holes". I actually think the colour it is now works - it makes a transition from the over all brick to the dark green roof.
The attached photo is quick and dirty but will give you a sense of direction.
Hope this helps.
Our horse barn has the dark green with grey weathered board and batten...