Our landscaping business has Kubota, Scag, and Exmark mowers. I can't speak to JD or some of the other brands--I think you'll find the commercial guys go with brands where they have strong dealer support. For example, there's almost no Ferris dealers here but they are reported to be an excellent mower.
Our ZTR is the Kubota ZD326--we chose this unit for several reasons, among them was that the deck adjustment is hydraulic and is quick and effortless compared to the Exmark. I would strongly urge you examine this on all models: how do you set the cutting height (an infrequent task) and how to you quickly raise and lower the deck to a parked position (a much more frequent operation as you load/unload or go over obstacles).
The ergos on the Kubota are excellent as is the ride--seat has multiple adjustments.
We use striping kits and the Kubota 2xx series was not available with striping, only the larger-frame 3xx series.
You can get a stamped (cheaper) deck or a HD deck for more $$. Be sure to compare what kind of deck you get.
It is VERY thrifty with fuel, which we can buy for off-road use and save compared to normal pump prices. However, diesel is still way more expensive than gas up here.
The Kubota is more difficult to change blades on than any other mower we have. Since we change the blades daily that's something of an issue.
The Kubota can be fitted with a hitch to pull simple lawn-tractor style attachments. I have not done this.
The Exmark can be fitted with a front-mounted spreader to put down fertilizer, ice melt, or sand. This unit won't fit the Kubota.
The fit and finish of the Kubotas is exactly what you would expect. The mechanical engineering aspects of our Exmark and Scag mowers, on the other hand, seems clumsy and amateurish in many details.
