On the show, Bran's powers are more about knowing things than doing things (the books deal much more with his warg nature than does the show, though so far to relatively little ultimate effect), while dragons are pretty much the opposite.
Bran's powers are difficult to casually observe (he said he'd seen Littlefinger do various things, for example, which Littlefinger would certainly know werewas accurate, but who else would?). Even those who know what he can do might not quite grasp the scope of it-- he can observe events in the past, which is easy to appreciate, but he sort of knows everything that's ever happened in Westeros (possibly subject to some unknown limitations). That's a lot harder to wrap your head around, especially in a setting where knowledge of history is limited to what someone may have written down in a book that happened to survive and which you happen to have had the time to read.
It seems like a fair bet that there are a lot of actual opinions about Bran's abilities. Many probably doubt that he can actually do any of the things he claims he can, and doubt magic more broadly. Others may be more willing to believe that his claims are at least possible. But the main characters of the show have nearly all encountered legitimate magical powers, many of them a lot more unnerving than knowledge of history and current events.
Seeing Arya drink lethal poison and survive, or mystically change faces, or watching a priest raise someone from the dead over a dozen times, or experiencing the mysteries of the House of the Undying, or a woman walk into a bonfire and then rise from the ashes, or seeing a dragon roast most of an army, or watching a field of corpses rise and attack-- these are all pretty dramatic and way outside of the norm of what people believed was at all possible. Bran's powers seem a bit more "ordinary", sort of like having extra-fast ravens or having spent a lot of time studying.
Finally, whatever it is that people believe Bran can do, he seems to be very much on his observers' side. At a minimum, he doesn't seem to be a threat to them (compare with a few dragons, which are inherently dangerous even if they are on your side).
So, in summary, Bran's powers are less dramatic, harder to truly understand, difficult to observe, and less threatening than essentially all other magic seen in the show.