Barkwood is darker but appears to have a bit of red in it. Hard to tell for sure on a computer screen. At some point you might consider painting the garage door the same as the siding. It would help pull focus off of it. Also, a garage door with windows would look great with you house.

bump...

Here is a photo with Barkwood.

Here is Mission Brown:

Based on houssaon's photos on my screen, Barkwood seems to fit best with your request for a deep brown. Mission Brown appears to have some gray in it and seems far from a deep brown. Again, monitors can be tricky.

Barkwood would be the better between the two, although it might have more red/orange in it than you want Ask your roofing contractor for a list of addresses in your area, they should have record of homes they have put those colors on. It is helpful to see the shingle colors in person, on a larger scale. For example, we felt barkwood would be a good fit for us based on the sample, but once we saw it on an entire roof, we realized the color wouldn’t work for us. We ended up with weathered wood, which is lighter than what you are after.. Do you need to use a GAF product? You may have better luck looking around. From my memory, there were a lot of medium brown options, but not much for dark browns (it felt like the choices jumped from mid browns to black).