What you end up purchasing will depend upon several factors. Weight and price being very important.
I have a mile long gravel driveway. Straight as an arrow with a deep valley in the middle. I use three implements to maintain my driveway.
My Rhino 950 rear blade is 96 inches and 1050 pounds. Clean out the ditches - maintain the crown - clear snow. This implement takes lots of practice if you plan on using it to smooth, level and maintain the crown. It's because of the design of a rear blade. Picture a teeter-totter. One side goes up - the other side goes down. That is how the standard rear blade works. Even with my hydraulic top link - crowning my driveway can be a real PITA.
My Land Pride LPGS ( land plane grading scraper ) does a great job of smoothing everything out. It will NOT create or maintain the crown. It does nothing for ditches or clearing snow.
It weighs - 820 pounds.
My Land Pride ROBB ( roll over box blade ) is used to move material from here to there. Example - I pull gravel up and out of the driveway ditches with the rear blade. I use the ROBB to collect this material and move it down the road - to low spots. It weighs - 800 pounds.
How heavy does the implement need to be. Depends upon what the surface of your driveway is. If it's loose gravel - a lighter implement might do a fine job. If it's like my driveway - rocks, gravel, sand, silt & volcanic ash - think concrete when it's dry - then you need the heaviest implement you can afford and that your tractor can handle.
With my first tractor - I had a lighter Land Pride rear blade ( around 400 pounds ). It did great on clearing snow - struggled to clear the driveway ditches - was USELESS on smoothing the driveway or maintaining the crown. It just skipped along and created sparks while being pulled down the driveway.
In 2009 I bought my new Kubota
M6040. I also bought the Rhino 950 rear blade. This blade is heavy enough to cut thru the surface "crust" on my driveway. Being heavy does not "fix" the teeter-totter effect though. Every time I use it to smooth or work on the crown - it's a fight between the teeter-totteer effect and my hydraulic top link.
So..... it was either get a rear gauge wheel for the Rhino rear blade or get a new LPGS. I choose to get a new LPGS.