I am looking at both and don't know if the Kubota is worth the extra money. I only mow 2 or 3 yards a week, one being 5 acres with inclines. I want the best machine for the money and the one that will last the longest with the least amount of problems. I have drove the 757 and it is the smoothest mower I have been on as far as the hydralic system. I have not drove a ZD 21 yet though. I did a search and it seems people are split on the ZD 21, but need to know for sure before I put out any money.