I think my roof is either black or a really really dark green color, my house exterior is mainly just black/white cause there's a rainbow flower garden around it so I didn't want the house to distract fromt he flowers much :>
I don't intend to change this anytime soon cause I actually like it quite a bit!
My main character's is red and always has been, always will be. It's my favorite color and there was really no question what it'd be. I use the brick siding with it and it looks quite nice! My 1st side character's is blue (to contrast the red), my 2nd's is pink (because she's super girly), and my 3rd and 4th have themed roofs (tropical and spooky, to match their house themes).
Also, I'm guessing someone has already answered by this point, but just in case- you'll be able to change your roof color freely eventually!
EDIT:
Here's a pic of my main character's house! It's simple and cozy and looks nice beside the apple trees ☺