I’ve had a ZG127 54” and now have a ZD331 60”. Both bought used.
What’s your intended use? Residential or commercial for a lawn business?
I had small issues with the ZG but nothing major, it just seemed like every year during the summer I would have to fix something small. Starter, a few spindle bearings, deck belt, crankshaft bolt kept coming out and dropping the PTO clutch.
I grease the ZD about every 10 hours, other than a full service when I bought it. Which I do on anything I buy used. The fuel usage on the ZD is great. The ZD is definitely overkill for my yard and I definitely couldn’t justify it to buy a similar model new so I found this one at a good price, it was listed for sale in January.
Commercial users especially that have multiple mowers tend to run the mowers until the warranty is up and trade them in. To have less down time with broken equipment and for tax purposes. I’ve seen on other forums there they are likely to swap brands biased on the service during that warranty period from a dealership more so the actual brand of equipment.