That is usually the major question. Should I use flash or HDR? Well, to tell you the truth, I really hate HDR! It just doesn’t fit my photography style. Here is a perfect example. The above image was a 7 exposure HDR image of one of the Pitts Biplanes. It is an adequate shot, but nothing special by any means.
When you use flash, the photo takes on a whole new life. The plane seems to jump out at you and the background colors are much more vibrant. Please do let me know which of the images you prefer.