The worldwide network of neutron monitors (NMs) is the primary instrument to study cosmic-ray variability on time scales of up to 70 years. Since the 1950s, 147 NMs with publicly available data have been in operation, and their records are archived in and distributed through different repositories and data sources. A comprehensive analysis of all available NM datasets (300 datasets from 147 NMs) is performed here to check the quality and consistency of the data. The data sources include World Data Center for Cosmic Rays (WDCCR), the Neutron Monitor Database (NMDB), the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN) and individual station/institution databases. It was found that The data from the same NM can be non-identical and of different quality in different sources. We give and tabulate here a recommendation for the optimal data source of each NM. We also present here a list of 29 ‘prime’ stations with the longest and most reliable data. Verified datasets for these prime stations are provided as supplementary information.