Your shingles appear gray. With the dominant pink tones of your brick and grey shingle already at play chose white as your trim. A neutral white is really the only safe choice (especially with white garage door), that or the other neutral: black. Adding anything else will look a bit odd. I personally love black as an accent color with brick but not everyone does. And grey trim will likely just look underwhelming. With some luck a houzzer will post the choices on your pic with some digital wizardry so you can see the options.