The best type of lawn aeration is either core aeration or liquid aeration. Core aeration is a proven method that allows water and nutrients to penetrate your soil to create better conditions for grass growth.
Liquid aeration is a growing alternative that can be more effective for seemingly healthy and established lawns. Click here to learn about liquid aeration.
You should also seek a company that does double-pass aeration—this will provide twice the plugs allowing more nutrients to reach the roots. Bonus points if the company offers both services.
You should find another provider if a company says they perform spike aeration. Spike aeration can make compacted soil even worse and is known to do nothing to improve the health of your lawn.