Some things to look for....
• When your deck gets above ~36" it gets really important to have the anti-scalping rollers on the corners of the deck. The reason is that as the deck gets bigger, the distance between the vehicle wheels also increases. This makes it easier for the deck to cut MUCH lower (e.g. "scalp") than the vehicle wheels intended.
• On discounted models the brackets for anti-scalping may be there, but they want you to buy the wheels separately. With fasteners that may be as much as $25 per wheel. And, a big box store probably does not stock the wheels.
• Users have reported issues with the new Kohler engines, and are very unsure what's going on with B&S now that they went into bankruptcy. They are both good names, but you may need to be slightly more attentive to your maintenance in order insure a long life. Oil changes, keeping the cooling fins clean, etc.
• Don't buy a ZTM if you have steep topography on your property. Since 2 wheels do everything on a ZTM it's easy to loose traction and slide (especially sideways) on steep grades. This problem with sliding is more prevalent on the lighter models under ~500 lbs. Once you get above ~700lbs they get far more sure footed.
• One of the items I love the most about my ZTM is that the foot plate lifts up to aid general debris cleaning and belt replacement. I like to get the leaf blower out when I finish mowing and the ability to lift this plate is a big plus.
• One of the things to look for is rubber insulated struts between the body and the deck. My 36" Hustler was the loudest thing, and I finally figured out the engine was pulling the entire deck to the rear via the drive belt.
Not once, but continuously ! It sounded like someone beating on a garbage can with a hammer. The deck has to be free to go up-and-down, but should NOT be free to swing front-to-rear.
• Look at your on-board storage. I carry a cell phone, a can of fire ant poison and a set of long-reach pincers. You probably have items you'd like to carry. Take them with you and make sure they fit onboard before buying.
Hope this helps.
It's bad when the official cup won't fit the cup holder.