This is an old enough thread that you may have painted it by now! I wonder what you chose.
I tend to focus so heavily on getting everything clean and neat, and then dress them up later. Sometimes I may just go all white in a case like this, but simply with all details attended to and everything clean and bright, it looks just great! Kristin mentioned this idea of doing what your endgame points you to; I try to stay efficient and add more cash inside the units to make them nicer for my tenants.
If you're still looking for thoughts, I'd look under the vinyl. If it's possible to remove even some of it, I would. (Like just the whole front face). If not, get it scrubbed clean. You can then use white as one of your colors. If you're all done, post up some afters maybe!
It may be possible to cut the vinyl back to expose the original trim around the four upper windows. That will help get old proportions back. This place will look so great with a period door on it and good windows. If you are doing vinyl windows, you may consider white trim around them because it will be less obvious they're vinyl (not old). If so you can still do a bit of color on a small supporting horizontal trim piece above/below. Quarter-round sized. This would be your third or fourth color in a multicolor scheme.
I can't tell: Brown roof? A buttery cream may be your good second color. Blue/gray? Perhaps a similar but lighter cool gray.
If you paint the bargeboard, you can paint the horizontal strip across that completes the triangle the same color.
My opinion is you can get away with paining the brick a color other than white but not too dark, creating a hovering triangle.
Much will be determined by what you can do with the vinyl. I would paint metal but am skeptical about longevity of paint on vinyl. Maybe it will buy you "just enough time" and you can do another round of cleanup in five years.
ps. If there aren't tenants there, I pull off all the co-ax and the dishes. Then I require that I am (somebody is) present for any re-install. They routinely place new cable anyways and can be teachable as far as not drilling in woodwork or otherwise making a mess of an old building. So you start fresh and get it where you want it.
I would prime and paint with metal primer the vent and the bit of flashing.