Use scientific method rather than opinion for research, it'll work a lot better.
Well, actually historical method would be better for a historical question. So, it's very dodgy to rely on a single piece of evidence, especially newspaper reports (I'm amazed that some people put so much reliance on the reports of provincial newspapers, when the rest of PPRUNE is full of paranoia about journalists). Historians know that the first thing to do is to evaluate the quality of the sources, and that individual pieces of evidence may be wrong by error, misreporting, or fabrication. Often you can't get a decisive smoking gun, but you can hope to work by triangulation.
The evidence for the Wrights' success in 1903 is not conclusive, if you want to interrogate it suspiciously, but it forms part of a consistent pattern of flights with gliders before that date, and undoubtedly successful flights after that date. OTOH, the claims of Whitehead are too good to be true, especially in the absence of any subsequent history of success. Pearse's dates are contested, which is not surprising, but even if he did fly in 1903, he's not historically very significant, because he's so out of the line of development.
As Pearse said, following Samuel Smiles, the notion of a single inventor is mistaken, and the Wrights' claim to priority is, historically, most significant for its effect on aeronautical development in the USA; but their really isn't much point in replacing them with some other claimant for first successful powered flight, given that the answer is to a large extent predetermined by the definition of "successful".