  We present a new catalog of Kepler planet candidates that prioritizes
accuracy of planetary dispositions and properties over uniformity. This catalog
contains 4376 transiting planet candidates, including 1791 residing within 709
multi-planet systems, and provides the best parameters available for a large
sample of Kepler planet candidates. We also provide a second set of stellar and
planetary properties for transiting candidates that are uniformly-derived for
use in occurrence rates studies. Estimates of orbital periods have been
improved, but as in previous catalogs, our tabulated values for period
uncertainties do not fully account for transit timing variations (TTVs). We
show that many planets are likely to have TTVs with long periodicities caused
by various processes, including orbital precession, and that such TTVs imply
that ephemerides of Kepler planets are not as accurate on multi-decadal
timescales as predicted by the small formal errors (typically 1 part in $10^6$
and rarely $ > 10^{-5}$) in the planets' measured mean orbital periods during
the Kepler epoch. Analysis of normalized transit durations implies that
eccentricities of planets are anti-correlated with the number of companion
transiting planets. Our primary catalog lists all known Kepler planet
candidates that orbit and transit only one star; for completeness, we also
provide an abbreviated listing of the properties of the two dozen
non-transiting planets that have been identified around stars that host
transiting planets discovered by Kepler.
