Sickle Bar Sickle Bar Mower for B7510

[CBW1999]

Any ideas on what size/model would be best for my tractor? What are the benefits of 3 point compared to the tow behind style?
I have a Kubota B7510 (21hp) will be mowing fields, some slopes and roadside ditches. Eventually I hope to use it for haying 2 to 3 acres.

I priced a used "newer" model at 2500. I have seen many other older/serviceable ones for much less. I would prefer to spend as little as possible/reasonable for the mower, not entirely because I am cheap, but I am fairly good a repairing/maintaining things.

Thanks for any and all help!