I've seen both White House Down and Olympus Has Fallen. Rated it a 9.
As far I am concerned, Olympus Has Fallen was the far better film. It took itself more seriously, the action scenes were performed more realistically than in White House Down and I found Gerard Butler to be a better protagonist than Channing Tatum.
Don't get me wrong, I found White House Down to be entertaining, as a light hearted, buddy action movie.
It's just that I enjoyed the subtlety and depth that was in Olympus Has Fallen more.