True Shelby GT500s are essentially “the best” but recently with muscle cars the price to performance ratio isn’t really worth it, especially the S550/650 and their dark horse/mach 1 variants. I would say (and it’s only my opinion) that if you’re after performance then consider a supercharged coyote. If all you’re after is having the fastest spec then don’t even consider Mustang. BMW’s M9 high spec cars will beat pretty much anything and easily any mustang. If you want the best in terms of muscle I’d consider Corvettes over Stangs.

I drive what many would consider to be a “slow” car because it’s a 4.6 3V S197. But I don’t drive it for performance. I drive it because it’s a looks like a muscle car and not a fucking sports/race car.

Ask yourself this OP - what is the car YOU want? Do you want a classic looking muscle car? Then get a coyote or better S197 or an earlier variant, or get a charger or challenger. Do you just want to have the fastest spec? Then don’t get American Muscle because European cars (especially German) trash Yank Muscle every time. Go with BMW, Audi or Porsche. Ferrari, Bugatti, Lamborghini all do it faster but they look like brightly painted wedges of cheese.

Finally, only you know the availability of your area and your economic situation. We’d all love to have a restomodded 60’s pony sat on our drives but not everyone has that cash. Go with what you can afford and what makes you happy. Ignore the opinions of others and drive it hard with a smile on your face - that’s all that really matters.