The driver's seat is the reason I bought my GX 470
I had a Touareg that had a great seat; the lumbar support adjusted up and down vertically in the seat back and the heater heated the lumbar support as well. When my small local dealership closed I switched to a Lincoln Aviator. The Aviator seat was terrible for me and I had a backache every day when I arrived at work.
I went to the Indy auto show last winter and sat in every luxury SUV that would tow a boat. The GX had a great seat for me. I'm 5'8" and adjust the seat cushion at maximum height, and the seat back fqairly straight- kind of like a dining room chair with arms. I haven't had a back ache with the GX at all.
The GX is the best SUV I have owned, so I hope you can get the right sear adjustment for you.