The most effective kind of two-stage system is the “cyclone,” which uses a funnel-shaped drum as the separator, or first stage. Dust spins around the outside, which gives bigger particles more of a chance to settle out before the smaller stuff escapes to the filter stage. If you can afford one, buy a cyclone dust collector.
If you can’t afford a cyclone dust collector, buy the most powerful single-stage collector you can afford, with a bag or cartridge filter that will trap particles as small as 2 microns. Connect it to every machine in your shop. If it is big and powerful, you can connect it to multiple machines permanently, using a series of hoses and junctions, with blast gates to direct the airflow where you need it. With a smaller collector, you can roll it around and connect it to the machine you’re using. Long hoses sap suction, so keep the hose short with smaller dust collectors.
What no one disputes is that capturing dust at its source, with powerful suction and fine filtration, is the best way to clear the air in your shop.