Light bit of science on this one...
data taken from all summer tyre tests on tyrereviews.co.uk (dates from 2009 to 2014, only looking at tyres deemed 'high performance', 'ultra high performance' or 'max performance')
http://www.tyrereviews.co.uk/Tyre-Tests/#summer
this is the number of times each manufacturer has came 1st in the test, (sample size is 33 tests)
Continental has won a whopping 13 times
Pirelli next with 6
Goodyear with 4
Dunlop, Nokian, Hankook and Michelin with 2 wins apiece
Vredestein and Bridgestone with 1 win each.
So on that evidence, clearly Continentals are the 'best' tyre (of those, 9 are contisport contact 5s, the other 4 being contisport contact 3s, which was replaced by CSC5)
However now for the disclaimer - while most tests are a combination of dry and wet performance, braking, handling, NVH and so on, each test will be slightly different -
Secondly (and most importantly) not all tyres were available for all tests. However i'm sure if MPSSs were entered in every one, they would have wiped the floor with everything else As it was MPSSs only won overall twice, out of 33 tests.