
One of the questions I keep up my sleeve for meeting new people, especially those of the geekier persuasion, is what superpower they would choose, if they could draw from their imagination or anything across the different popular superhero universes. It's a fun question to think about, and is also a cutesy icebreaker for geeky dates, the kind of creative question with well-thought-out answers as well as quick snappy punchlines. The most popular answer to this is, universally, teleportation. (There have been studies!!) Who wouldn't want to bypass plane flights, or even having to get into the car to go to the KFC? What if I didn't even have to get out of bed to get a Pepsi from the fridge?
In the most realistic sense, the best answer to the question is having the magical abilities of a character like Dr. Strange or Zatanna, which encompass most of the more desirable superpowers altogether: most magic users can also teleport, summon things into existence including unlimited wealth, fire off incredibly powerful spells etc. The superpower equivalent of wishing the genie for unlimited wishes. Notably, though, Zatanna always loses in a fight with, say, Superman, because by the time she can cast a spell the Man of Steel has already zipped across the room and punched her through a wall.
So, the correct answer in a combative sense is always speed. Super-speed will best nigh all other powers in a battle; what good is Superman's strength if he can't hit you? DC, always on the bleeding edge of preposterous nonsense, have written themselves into a hilarious corner by making their various speedsters into something akin to invincible demigods. In the DC universe, speedsters tap into the "Speed Force," a nebulous all-encompassing does-whatever-the-author-decides-this-week sentient cosmic energy field that allows specific entities to move at the speed of light or beyond. "Beyond" is the functional word here, as the bar has been raised across the decades of Flash and Flash-adjacent books so that the different speedsters' feats go far beyond the point of absurdity. Functionally even the strongest heroes and villains are rendered inert by characters who tap into the Speed Force and use it to its full potential; Superman can't get anywhere near the speed of the Flash, and since Force equals Mass multiplied by Acceleration (F=ma) various speedster characters can essentially put their fist through Clark's head. Taking this to its preposterous extremes have left DC's fast-moving heroes, and villains, in a league of their own, to the point where evil end-of-the-multiverse villainous mastermind The Batman Who Laughs summoned a small army of evil Flash-lites called the Lightning Knights to take care of the speedsters during the dumbass Dark Nights: Death Metal storyline. (Why they weren't summoned to take care of, y'know, everyone is the reason we defer to yo's often recited "Poor, sad, stupid, dumb DC" quote when talking about this nonsense.)
But Quicksilver is considerably different to the various Flashes. Let's take a look at a page from X-Factor #87, the single issue that has most defined his character for three-plus decades:
Like he says himself, "not everyone can raise arrogance to an art form."


He looks about 60 in that comic, which absolutely fits the relativity problem of moving faster than light.
Also his father was born sometime around 1930.
I think the Flashes get around relativity because of Speed Force magic (the same reason they don't need to eat thousands of calories per minute). Quicksilver does it by having a max speed that's not even 200 mph...