Best way to purge air from hydronic heating system?

Thanks to this forum and especially to NJ Trooper, I've made some major recent repairs to my heating system (new larger expansion tank with service valve, aquastat relay, shutoff valve, partial new piping), it's running very well. However, I'd like to add a device to the system that eliminates any air in the system. The radiators have manual valves that open with the key, but that gets old pretty quick.



I know there are whole-system air eliminators and also auto-air vents (like the ones linked below) that install in place of the manual valves on the radiators.



417-3 - Taco 417-3 - Coin Vent



0590712 - Watts 0590712 - 1/8" HAV Auto Air Vent w/ Manual Override



508013A - Caleffi 508013A - 1/8" Automatic Hygroscopic Air Vent



Can anyone recommend the best solution? Not looking for a shortcut or band-aid, I would rather purchase something that is robust, efficient, and low-maintenance.



Thanks!

Best way to purge air from hydronic heating system?