When I first started out I bought a used Ryan IV aerator. Worked great for me. I had some larger lawns, so I bought a used Ryan V aerator. Poor design, chain broke a few times (one chain vs. two with the smaller Ryan IV model).
Then I bought a Lawn Solutions aerator. I get 50% more lawns done with the LS aerator because is goes forwards and backwards WITHOUT having to lift the tines and turn the machine around. They are a sponsor-check out the video.
The people who say they like other aerators have NEVER tried the LS aerator.
Obama is so bad, Kenyans are accusing him of being born in the USA.