Just my 5 cents:
I'd asked the same question about accuracy of 9mm few years ago and got no certain answer. Then I began testing myself. I bought 3k of SPEERS 124gr ammo and during the following year I tested few pistols in the same manner: 25m distance,alone, one hand, standard CSSA bullseye target, 3 series of ten shots in slow fire with 10-15 minutes rest between series. After 7-10 days I repeated the test. Finally,for pistols I possessed I had data of 180-200 shots for each and for pistols I borrowed - 60 shots. On completion of really hard job the results are:
STI Targetmaster 94.7%
HK USP Expert 91.3%
Beretta 92 -89.8%
CZ-85C - 84.2%
Glock-17 - 82.6%
Springfield XD - 80.5%
All above- mentioned stuff only means that some pistols are better for me, some - no.