  Integrated photonics is a powerful contender in the race for a fault-tolerant
quantum computer, claiming to be a platform capable of scaling to the necessary
number of qubits. This necessitates the use of high-quality quantum states,
which we create here using an all-around high-performing photon source on an
integrated photonics platform. We use a photonic molecule architecture and
broadband directional couplers to protect against fabrication tolerances and
ensure reliable operation. As a result, we simultaneously measure a spectral
purity of $99.1 \pm 0.1$ %, a pair generation rate of $4.4 \pm 0.1$ MHz
mW$^{-2}$, and an intrinsic source heralding efficiency of $94.0 \pm 2.9$ %. We
also see a maximum coincidence-to-accidental ratio of $1644 \pm 263$. We claim
over an order of magnitude improvement in the trivariate trade-off between
source heralding efficiency, purity and brightness. Future implementations of
the source could achieve in excess of $99$ % purity and heralding efficiency
using state-of-the-art propagation losses.
