I certainly agree with everyone who said don't get a ZTR. For the price of a decent ZTR, you could almost buy the right tractor for what you need and have something A LOT more useful. In fact, I would not even do business with the dealer who recommended a ZTR for your needs. He clearly cares more about selling SOMETHING than he does about meeting your needs.
One thing that you, IMO, should keep in mind here is that if you buy a decent quality tractor, you will probably never have to buy another one. Try not to be too price driven on this issue, if you can avoid it. A couple of thousand extra dollars spent now might well save you $10,000 down the road a bit.
I have 3 horses and 40 acres. 20 acres or so of this is woods so it sounds like I really have pretty much what you have. 3 horses and 20 acres that require some degree of maintenance. I do like to brush hog in the woods but have about decided the tractor I have is not suitable for this job.
I agree that you will probably find you don't need to mow your pasture as often as you think. I probably mow mine 4 times a year and I use a brush hog. I have a 60 inch MMM for mowing the yard. I do have a FEL and wouldn't be without it for mucking paddocks. I was a little hesitant to spend the extra money for the FEL but I use it all the time. It is hardly ever off the tractor.
I have a
BX2230, 60" MMM, 4' bush hog and a FEL. If I had 20 acres or so of yard and pasture, I really think this setup would be just about the perfect compromise. Add in my 20 acres of woods with lots of 1 - 1-1/2 inch thorn tree saplings and I would no longer come to the same conclusion. I believe I spent about $13,500 for the tractor, MMM and FEL plus another $600 for the brush hog.