Britain retains controld of the Faulklands for a reason, and the rest is history. Who is to say which country actually had more control, however Britain did win claim, thus clearly, Britain had more control. Original claim is still disputed, along with discovery. No one really cared about claim until the British.
Spain only partially controlled the Falklands under 50 years, from 1767 until 1811. Partially, because the British also maintained a presence on the islands during two parts of this period as well. Britain however has had sole and uninterrupted control of the Falklands (excluding Argentina's brief occupation during the Falklands War) for over 150 years since 1834.