Aerator

[fms]

I'm looking to purchase an aerator and looking for information on options.
I have a John Deere 2305.
What are the pros and cons of a aerator that hooks up to the tractor vs. a walk behind?
How much difference is there in price between a walk behind and a tractor model?
Doing a site search I've read several recommendations on walk behind aerators, but very few on tractor mounted aerators. What models are people using for a tractor the size of the 2305 and about what did they cost?
Thanks.