I think the winner would be the Flash (Barry Allen). They are both super fast and both can travel through time. However Quicksilver can only travel to the future (up to 12 days ahead of the present). Flash can go back in time as well go into the future. Also, if you still don't agree with me, Flash has beaten Quicksilver in a race (In a crossover)...So... They both are really cool, but I think Flash would win