Another thing to consider is they do have snow plows for ZTR's. I have only ever sold one. The guy that bought it was in such a hurry to get it, he paid me for it and picked it up from my distributor. I asked him to let me know how it worked....never heard a word good or bad.
Before we started selling ZTR's we had tractors. First one I cut our property with was an old Jacobsen. We eventually got a JD 318 and then later on a 420. The 420 had a 60" deck. I could generally cut our property in about 1:45 with that machine. I can do it in 45-50 minutes flat with a 60" ZTR. I can also do it in 45-50 minutes with a 52" Wright Stander. The Stander is just quicker around obstacles(which we have alot). If it was wide open mowing the ZTR would win. The 420 had a very heavy stamped deck that would bog down causing slow downs in taller/lusher sections of grass where the commercial ZTR's do not have to slow down.
As someone else said, if you want access to lots of attachments go with the tractor. If you are just trying to get the grass cut, go with the ZTR.