Today at the auto show, I felt like the 2019 Envision's seats were extremely hard and had random pressure points in my back. Lumbar support was good though. Maybe they changed something with the new 2019s, but I remember the pre-refresh Envisions had good seats. Everybody has their own opinions with seats, but the Buick's were very hard. I didn't sit in a Lexus today, but I know their seats are much better. I'd check out the RX. Honda's are very good, too, in the CR-V and Pilot.
I think the seats in the CX-5 were OK. Well-bolstered, but not what the OP is looking for. Mazdas usually lack in thigh support and that has been changed with the 2020 Mazda3.
Once that BMW breaks, it will also break your wallet. They are much more expensive to fix than most other brands.
I rented a QX60 last month and drove it over 1700 miles in three days. Very good leather seats and soft ride, but the interior is so old. Thigh support was super good. A loaded Pathfinder is a better deal. Really, all unibody SUVs are slightly lifted shortened station wagons. You'll get a great deal on these. It is well-known that Nissan makes some superb seats. The rest of the car is average.
You need to sit in all of them because everyone is different. We can only tell you what SUVs are actually good objectively.
My top three for you are the Lexus RX (or perhaps Toyota Highlander), Honda Pilot, and maybe a used Envision.