With the Scag it's the seat and the Turf Tiger II has a very low center of gravity. I fell in love after 1 pass on the demo.
I've wandered about them. I did check out a ex mark and John Deere recently, both were nice, but not a lot better than my yazoo.
That is a similar seat that came on my wife's Z997R, it is completely inferior to the Grammar MSG65 that came on my Hustler HyperDrive. That twist to adjust seat isn't bad, but it is not even close to the same ride. Although you have to manually pump the air up onto the air spring with your butt in place, it gives a much nicer ride. If you opt for forward aft isolation really makes a huge difference too.
Right after the first surgery, I did hire it done. Needless to say, I can't afford that all summer. 1k a month for mowing is a little steep for me.
That is the seat, it appears not to have the fore/aft isolator and it has the optional upper back rest. They don't come cheap, probably why Hustler stopped putting them on standard on the HyperDrive a few years back.
What you need then is a tractor style mower, a quality machine, not an mtd, or cub cadet. It will be slower than a ztr, but will be far less painful on your back.
The cloth Grammer seat shown in the photo does not have the fore/aft isolator of which is really the game changer for ride quality. The Grammer seat shown in your Northern Tool link does have the fore/aft isolator that can be locked out or used in the front to back suspension mode by utilizing the flat gray lever on the bottom left side when sitting in the seat.
