Bad Boy. Fantastic super high quality mowers. See the link below.

Here is a link that might be useful: Bad Boy Mowers.

Wright Sentar
I've been in the lawn/landscape business since '88 and the Sentar is the best I've ever used. I use the Sentar Sport 36" deck because most of my properties are smaller, but it is available with larger deck sizes.

The design of this mower is definately different. It does take some getting used to. I felt it handled more like a walk-behind than a traditional ZTR. You can work the balance of this mower much more than a regular ZTR.

This mower appealed to me mostly due to its compactness, speed and agility, and the ability to sit or stand while mowing. Being able to change positions really helps to cut fatigue & I think it also improves saftey by giving me the ability to stand & get a better view in tight places. The mower is the easiest to mount & dismount too. Also, you have the ability to bail out if necessary (nothing that bad has ever happened to me, but knowing I can get off in a hurry is nice.)

Darrin

Here is a link that might be useful: Wright Mfg. - Sentar

I had a similar situation, only 3 acres. After much research, boardering on analysis paralysis, I went with a Dixie Chopper Silver Eagle LT2700-60D. Out the door price of $6999 plus tax. Each of the approx 7 hours on it have reinforced in my mind that I 100% made the right call.

I found that comparable competitor units (JD 717/727, Scag Tiger Cub, Exmark CT) were $1000-$2000 more, less warranty, and/or fewer ponies. Also, the DC dealer blew the others out of the water in product knowledge and in how I was dealt with.

I also really liked the Bob Cat Fast Cat (much better & heavier built than CC Enforcer) and was leaning heavily toward it. But in the end, I felt 52" was a lot of deck for 19 HP, regardless of the fact that they were Kawasaki horses. If they offered a 23hp Kawa for the same price ($5989), I probably would have gone that way.

Here is a link that might be useful: DC Silver Eagle

I will echo D Bear's opinion. I went with the Dixie Chopper and love it. I have some steep terrain to mow so I added two 30 lb. weights made for a grass hopper to the front name plate on the Chopper and it really works well.

I'm not sure that it is the best, but like Darrin I am really impressed with Wright's mowers. They are unique and very well made. I use to live within 15 miles of their manufacturing facility in Frederick Maryland. Top quality company in my book.

Another to consider would be a Ferris mower with their suspension system is probabaly the most comfortable standard ZTR on the market.

I'll chime in for the Simplicity Cobalt. It'd be about $1000 over your budget brand new but if you bought last years model you'd be right where you want to be.
27hp kohler command twin, 2 year warranty, fully adjustable suspension front and rear, etc....
I can't imagine another mower having a better cut. The full width rear rollers are just icing on the cake.
I have one and wouldn't trade it for any other. Super fast and easy to operate.

Here is a link that might be useful: Cobalt

That Cobalt looks nice indeed. I bet it is made by Ferris with all the fancy suspension and all. Simplicity bought Ferris prior to being sold to Briggs and Stratton and I would imagine Ferris builds most of Simplicities ZTR line just like Snapper lawn tractors are all built by Simplicity. Nice machine.

Does anyone have experience with Scag, Gravely, Exmark or Hustler ZTR's?

All four of those are good. I've tried them all and can say that you just need to try them out. Their is not a best one per say, as their will be one that you feel most comfortable with. I could say that I like the Scag better for whatever reason and you might like the Gravely better for an entirley different reason. My suggestion would be try out as many as you can and then get the one you like best. Thise are all common commercial grade machines like the Wright, Dixie Chopper and the Ferris already mentioned. Another really well made machine is Walker. Very well made machine and users that have it really rave about them. None are head and shoulders above the other. They all have strenghts and weaknesses, but you really need to find out what priorities you have and match a machine that is strong in that.

For example, if comfort is your key then try the Ferris. If you are looking for speed, I hear the Dixie is about the fastest out their. If you want the most versatile, then it would be hard to beat the Wright. Best cut may go to the Walker.

For the most part I would say it is your personal preference. I have a Scag TigerCub with the 48 inch deck that I mow five acres with. I mowed my whole yard last weekend in 2 hours and 15 minutes. The thing is belt like tank and I love it. Here in Louisville it seems like everyone uses Scag or Exmark.

I was looking hard at the BadBoy Mower until my neighbor got a lawn service in to cut her lawn. They had a BadBoy Mower. The cut was terrible. Not just a little bad. I mean so bad that she was not going to pay them until they straightened it out. I realize that this may have been something wrong with that particular mower, but it turned me off big time. Too bad, because the BadBoy mowers really look like they are built very well.

The one thing that I would keep in mind is that if you are a homeowner, your machine is probably not going to see anywhere near the amount of use or abuse that commercial mowers see. Yes, it is really nice to own the best, but when the best is double the price of that which is adequate,you have to pause and think. I would have to say, from what I have seen, that if you have up to about 3 Acres to mow, one of the higher rated ZTR's at around $ 4,000 would work very well. I have owned a Simplicity Lawn Tractor for many years and it has served me well. I am looking close at their Champion model. I also hear good things about the Swishers, in spite of their low price.