Long time lurker here.
I grew up splitting wood and have most of my adult life. I've used both standalone and 3 point hitch. My preference is 3 point hitch as I like to use the same tool as many ways as I can. Having said, there are valid reasons to go with a standalone. For me, I'd rather not have another engine to maintain. But again, that is just my opinion. The biggest thing that I think, and others have mentioned, is get something that is vertical. The major reason for a wood splitter is to turn the manual task into a quicker, easier job. Lifting or rolling a round onto a horizontal splitter will wear you out. Having one that is vertical will save your back and make the job much easier after a long day.
I grew up splitting wood and have most of my adult life. I've used both standalone and 3 point hitch. My preference is 3 point hitch as I like to use the same tool as many ways as I can. Having said, there are valid reasons to go with a standalone. For me, I'd rather not have another engine to maintain. But again, that is just my opinion. The biggest thing that I think, and others have mentioned, is get something that is vertical. The major reason for a wood splitter is to turn the manual task into a quicker, easier job. Lifting or rolling a round onto a horizontal splitter will wear you out. Having one that is vertical will save your back and make the job much easier after a long day.