There are basically two types of grapples.....so analyze your needs, do some searching.....and decide what type you are gonna want.
Those two types are the "rake" type.....that dont really have "carry" capacity as the tines are short and stubby. Cylinders are usually mounted on the outside edges and behind the grapple, and push vertically to close the lid. They look like these
Compact Tractor Loader XTreme Root Rake Grapple for tractors up to 50 HP
Then there is the "root" type grapple with longer bottom. Better for carrying stuff IMO. Look like these
Compact Tractor Dual Lid Wicked Root Grapple from Everything Attachments
The rake types are better for pushing debris....root type better for carrying. Both do well with rocks, logs, and brush. I like my "root" type because it carries ALOT of firewood. Rake type wont.
After you decide the "type"......if you so choose the root type, you need to decide on single or dual top lids.
Singles are cheaper, simpler, and lighter. And work well for logs and brush. Dual types are more expensive, and heavier, but can grapple more things of odd shapes....or multiple logs at one time where a single might not bite on all you want.
Then its time for shopping. You can get grapples that will work very well with the MX for ~$1000.....or you can get a "better" one and spend 3x's as much. Everyone has their own preferences. I use tomahawk 66" single lid and I use it pretty hard. I think its a really good match for the ~$1000 it cost