48~50" fabricated deck. 10mph travel speed. 25 to 28 HP.
If you go bigger on the deck you need a dead flat lawn.
That points to the Ferris 600 or 700, or Simplicity Citation. I have the latter.
I agree with most of the advice about commercial vs the box store ztr's. AN rfm would be an option like the op stated. I have two Simplicity Citations, one with a Briggs and one with a Kawasaki commercial FX engine, both with mulching kits which I really like.
I see the new Citations are Briggs only.
Anyway, prior to the Citations I had a Simplicity Champion and I would suggest the op look at this model for price point. They now make two models of Champions both are upgraded from one I had. My dealer had them around $4200 and $4800 last year.
I'm just relating to brands I am familiar with and not claiming other brands don't have similar price point models that would also be of a similar capability / quality. The shocks on the Ferris and Simplicity z turns are nice.
Seven finished acres for the op is a lot of lawn and money spent now for time savings and durability would be worth a quality machine if budget allows. I know the op is not talking about the real low cost z turns, but I'll relate the following:
I have had people ask me about z turns and I tell them the prices and they might say that's too much or Lowes's has z turns for $2,200. I'll explain a little and then usually say if their budget is $1,500 to $2,500 they are better off buying the regular riding mower at Lowes or preferably I recommend the local dealer.
I said it to my neighbor this way. He had an old Cub Cadet (that he wound up nicely restoring) that belonged to his dad. He could not believe a z turn was $4,000-$5,000 or more for a decent grade. So I asked him what his dad paid for that Cub new in 1970-71. And he said it was around $1,000-1,100. Since my dad bought a similar one (I now use to pull trac vac). I had used an inflation calculator and told him that would be the same as you spending $5,000 or more now.
He went out and bought a decent JD from a dealer for around $4,200., that has and will serve him well. The point is at the time those old Cubs were the premium lawn tractor of the era and correlates in a way to these z turn costs now. And correlates that I must be older than I think I am!
But, IMO nothing beats the z turn. Although like Sawyer Rob and 4570man stated a front mount z turn could be the best...now those are expensive