I have this header image:
And I'm trying to find the best colors for the text of the title. Any suggestions?
I think that depends on other elements from the context. But orange is good if you want to emphasize the title.
To clarify, does the title sit in the header? Do you want your headings to use the same color?
I normally do a test to actually see what works best. I made a copy of your header and added some of the suggested colors. I also added drop shadows and outer glow, just experimenting.
My decision would be based on what I want to do with headings. If I wanted to use the blue for headings, I might use a glow around a blue title to simulate clouds. Or white with a drop shadow for most contrast. I like adding a layer style in this case, to help separate the title from the blue sky, since it uses pretty intense color.