I like German Muscle cars.
The Audi RS4 has a 4.2L V8 engine with 420HP.
It won many engine awards and it was on the 10 best engines award.
No other muscle car made it to the ten best engines.

All makes have had the best engines.Ford with the 351 Cleveland,Chevy with the 350,and Chrysler with the Hemi.Chrysler also put out the best 6 cylinder with its slant 6.The hemi has got to be the engine of choice.Most aftermarket race engines used in drag racing are of the Hemi configuration.Chrysler is not the only manufacturer but, I think they were the first with the 356 in the mid-fifties.Hemi is short for hemispherical which describes the shape in the head directly above the piston.Compared to other engines where this area is more flat,inside a hemi this area is round and spherical which allows for a more complete ignition thus producing more power with less waste.
You did ask about best engines;not just biggest.

i like the 426 Hemi personally.

I agree 427 big block chevy

I know it’s the most popular but have never had one. Only big block Pontiac and Chevy.
Myself, think I’ll go with Chevy BB. Better availability, lots of after market parts and plenty of raw power.

427 Chevy big block. This engine was in some of the Corvettes, Camaros, and I think the Impalas. There may have been others, as well, like the Nova.

427.