The Flash is undeniably one of the most recognisable superheroes of all time. I've seen people argue whether or not he is more of a pillar to DC than Wonder Woman, and I'm not here to discuss this, but the fact the discussion even exists says a lot about how important he is.
The CW Series being a big hit is the biggest proof that people love The Flash as a concept (unlike what Andy Muschietti had to say about it). In my opinion, most of his appeal is the same as Spider-Man's, that being he is a normal, relatable guy with everyday problems and hustles that gains superpowers all of a sudden. Also, Flash’s power is amazing because speed creates so many possibilities for both storytelling and action. It’s not just strong, it’s dynamic. His suit is equally great; simple, iconic, and it just works perfectly for who he is.
The Flash has decades of amazing stories to pull from, and the nature of his powers create so many possibilities. The stories got enough depth to stand on their own if they were a self-contained universe and it'd still be interesting. And don't even get me started on his power levelz I know there’s a whole crowd who sees The Flash as a literal god.
That’s why I think The Flash has the potential to become a huge success for DC. He should be a top priority. People are (rightfully) asking desperately for a Wonder Woman project, and The Flash deserves that same energy. And it doesn’t matter how recent the DCEU Flash movie is. The same way two Batmen can coexist if their tones are different enough (DCU and Reevesverse), a comic-accurate Barry Allen (personality and characteristics that wise) would feel totally different from the DCEU version. It wouldn’t even be an issue.