I work for a company that does both SVG+JS and Flash media, and there are some legit cases where we still choose to use Flash, because SVG can't reach the same performance — anything with lots of animated gradients, deep scene hierarchies, transparencies, masking, filter effects, or high vertex counts. SVG rendering in all browsers not named "Chrome" is crazy slow, and in Chrome SVG rendering is not pretty when you look closely at it.
But SVG is the only browser graphics tech with excellent tooling for illustrators (namely, Illustrator). So we've been forced to change both our art style, and our rendering stack, to deal with the death of Flash.
That's life in the tech industry, fine. But it's misguided to say that the browser is unequivocally better or worse performing than Flash. It really depends what you're making, and how you make it.
It's totally possible to make something on the web that looks and performs better than it would in Flash. But you have to put strict restrictions on what kind of art you use, and what technology you use to render that art, which puts restrictions on your production process, which sucks.