  Cosmological parameter constraints from recent galaxy imaging surveys are
reaching $2-3\%$-level accuracy. The upcoming Legacy Survey of Space and Time
(LSST) of the Vera C. Rubin Observatory will produce sub-percent level
measurements of cosmological parameters, providing a milestone test of the
$\Lambda$CDM model. To supply guidance to the upcoming LSST analysis, it is
important to understand thoroughly the results from different recent galaxy
imaging surveys and assess their consistencies. In this work we perform a
unified catalog-level reanalysis of three cosmic shear datasets: the first year
data from the Dark Energy Survey (DES-Y1), the 1,000 deg$^{2}$ dataset from the
Kilo-Degree Survey (KiDS-1000), and the first year data from the Hyper
Suprime-Cam Subaru Strategic Program (HSC-Y1). We utilize a pipeline developed
and rigorously tested by the LSST Dark Energy Science Collaboration to perform
the reanalysis and assess the robustness of the results to analysis choices. We
find the $S_{8}$ constraint to be robust to two different small-scale modeling
approaches, and varying choices of cosmological priors. Our unified analysis
allows the consistency of the surveys to be rigorously tested and we find the
three surveys to be statistically consistent. Due to the partially overlapping
footprint, we model the cross-covariance between KiDS-1000 and HSC-Y1
approximately when combining all three datasets, resulting in a $1.6-1.9\%$
constraint on $S_8$ given different assumptions on the cross-covariance.
