I did not own a V8 AMG, however I did own another German competitor, a 2022 M3 Competition xDrive.
The interior is definitely worse in the Caddy as far as materials go, mostly the armrests and dashboard leather material is equivalent to a 50k vehicle, the seats are lovely though and you do get carbon fiber free of charge in the center console and doors. BMW wanted extra for this.
The big thing about German V8's, at least modern one's, are they don't sound amazing. All the turbos muffle the shit out of the exhaust, the C 63 fares better but its still doesn't scream like an LT4. However the LT4 in the Blackwing only sounds amazing on the outside, you know where you aren't driving the car. The vehicle rides better and has sound deadening equivalent to a modern German vehicle and hearing that V8 roar is a step above a turbo German V8, but only a little bit inside the vehicle, its not as loud as I wish it was but thats just my opinion. LT4 > every German engine on sale today that isn't a 4L Flat 6 from Porsche.
As far as I'm concerned, the Blackwing wins in every metric over the Germans except fuel economy and interior materials. You say AMG is cooler, cooler to who? people who know what a C 63 is or an M5 probably also know what a Blackwing is, AMG or M, the brand has been watered down so much this last decade I don't know how anyone can think its cool.
If someone compliments your German AMG/M car it might be genuine, it also might be they see a badge and just associate that with great, but don't know anything else. Someone compliments your Blackwing, thats genuine, I'd also say its a very handsome looking sedan. A Blackwing is PEAK, "if you know, you know".
You see a Blackwing though...a MANUAL to boot, well, I think thats the coolest sedan on sale today. Defiantly cooler then a run of the mill AMG.
A Blackwing is 70% of the German car in terms of interior quality, 130% the German car in terms of driving dynamics, 120% the German car in terms of sound (interior) and 200% of the sound on the exterior, 120% the German car in terms of ride quality (Magride 4.0 is amazing) and 70% of the cost.
Oh, it also has a better warranty and doesn't lose 50% of its value in 4 years along with some painful repair costs down the road which is great if you want to keep it long term.
If you don't care about what badge is on the hood and you don't plan to put winter tires on it and you are fully aware that the interior quality won't be as nice as an equivalent German car, you will not be disappointment (except maybe wanting more interior cabin exhaust noise).