LOL, you and I are car-twins. I'm going RS Q8 from the S6, mostly for the options available on it: Carbon Ceramic brakes, Executive, B&O 3D, Cognac leather interior.
The SQ8 will fit the bill as well- it's the same Porsche 4.0 V8 with the same tuning potential (668 HP / 768ft-# on 91 pump) as the RS Q8.
Build options matter a lot to me on the 4M platform: You'll need the Executive package for full dual-pane windows, soft-close doors, and microsuede headliner. The B&O 3D audio was a $5K option and sounds similar to what we have in our S6. Try your best to find one with the S-Sport package, which gets you the sport rear differential and 48V mild-hybrid rear sway bar-- it's connected to actuators on each side that adds torque to the sway bar, opposite your turn angle, to reduce body roll. That's standard on the RS Q8.
Another thing to note on the 4M platform is a notorious issue of a failed 48V generator- it's most prevalent on 2020-2022 model years, popping up after 20K miles or so. It's an expensive repair out of warranty but I imagine AoA will soon issue a bulletin extending the warranty of the alternator and mild hybrid system.
I'm particular over the scarce few colors that truly look good on the Q8 body (to me): I only find appeal on Navarra Blue, Waitomo Blue, Java Green, and to be a basic bitch, Daytona Gray. SQ8 interior colors are limited to Rock Gray, Arras Red, and Black.