Mickey,
There are pros and cons with both - we just use a quad for rolling and chain harrowing and are using a local farmer for topping the fields. However this makes us dependant on when the farmer can come and top the fields which is not ideal as it sometimes doesn't fit with how we want to use the fields / move the animals around.
You can get powered toppers to tow behind the quad but prices of these seem to have gone through the roof recently almost to the point of being able to buy a tractor for the price of one of these toppers. Also the powered toppers only have a relatively narrow cutting width compared to a tractor mounted one - so it takes longer to cut any given area.
You could however do what we did last year which was top the fields with a sit on mower - now that takes a long time trust me but sit on mowers arent really designed for that level of abuse hence probably why ours has refused to start at all this year !!
There are other advantages of having a tractor - if you get one with forks on the front then you can use to move bales around and lift other things - if you wanted to try making your own hay then you'd probably be able to arrange to borrow a hay baler from someone. Also access to a lot more implements.
It is a big commitment though because you will probably still need a quad even if its just for towing and getting around.
We have hummed and hahh'd about getting a tractor so much so our local farmer got fed up with me talking about it and has offered to let us borrow one of his for the winter so we can see how much benefit we get from getting one ( and to shut me up...... )
Regards