I thought I would bump this question since I happen to stumble upon a CIA page that addressed the question.
It give a very politician-like answer along with an infographic about half way down the page:
*"Inevitably, any comparison of the two aircraft will lead to the question: which one is faster? There is lot of controversy among airplane enthusiasts as to which aircraft holds that title. There’s no simple answer.
The OXCART has a documented maximum speed and altitude of 2,208 MPH at 90,000 feet, set during a test in 1965, while the SR-71 holds the official speed record for a piloted operational jet aircraft of 2,193 MPH, set on July 28, 1976. On the same date the Blackbird set an official world altitude record of 85,069 feet.
Unofficially, of course, pilots of both aircraft have anecdotal stories indicating the numbers of both aircraft may be higher, and some SR-71 test reports show that the aircraft surpassed the official records for speed and altitude.
Nevertheless, both the A-12 OXCART and the SR-71 Blackbird are regarded as pioneering achievements in aeronautical engineering and the pinnacle of aviation technology during the Cold War."*