I see the RS7 and GTR popping up.
GTR is no where near the level of a Gen 2 R8. Over a Gen 1 yes I'd take the GT-R. It's a glorified Mitsubishi Evo with a "tad" amount of refinement. Personally I just don't own more than two cars at a time. Had a baby swapped out GTR for RS7. Don't miss the GTR really at all. The V6 engine note is not that great at all. The transmission is awful in the GTR.
GTR with FBO (full bolt ons) on pump 93 based on my VBOX is pretty much a neck and neck race from a roll. E85 it will walk away. Problem with GTR is it's exponentially expensive past basic bolt ons to make the car any faster. $7,000 will get you to low 10s at mid 130s but beyond that it's $50,000+.
RS7 is one of those "ultimate daily drivers." Sure you'll take a slight hit on the price at some point but pay to play. We love ours and for baby transportation duties (why we sold GTR) it's extremely spacious. E63 I like more but less rear room for a baby seat. Porsche Panamera just as good for rear space but cost of entry much higher and I think it's uglier.
RS7 with a tune will hang right there with the Gen 2 R8 V10 Plus. 10.5 @ 131 for R8, 10.8 @ 128.7 for the RS7. 0-60 only off by three tenths (2.5 R8 2.8 RS7). The video below is software alone otherwise stock. Plus, there's much more affordable modification pathways for the RS7 to make it easily faster than a naturally aspirated V10 R8 of any model/generation.
Friend got the hit and I followed along in Mexico in the RS7. Barely can pull away at best...