A simple drawn background is better than super imposing a drawing onto photograph. You're design itself isn't bad at all, but its clashing so intensely with the photo, and its being brought down because of it.
That being said if you're interested in exploring photographs as backgrounds: generally speaking, if you're going to be using a photo in a part of a drawing you should try and match the style of the photo to the style of the drawing. In the future, should you go this route, try dirtying up your character more, or getting a cleaner background image. Right now Taskmaster is looking way too clean for where he is. The level of polish and shine on his armor is at odds with the dusty city he's in making it feel even more disconnected. A good way to get around this is to use stark black and white photos and do your designs in black and white. Or you can use a specific coloring/shading technique and use a filter to adjust the photo to match your drawing, cellshading, comicbook style Ben-day dots (would fit if you're continuing with comic characters too).
Also a good rule of thumb is to take the photographs you're using yourself, because of licensing issues. Failing that, you can look for public domain images to use. (not saying this isn't, I don't know).
Hope this helps in some capacity!