Platformers. Is there any question?
At a point in the Amiga's life you could lift a doormat and a new Amiga platformer would come out. Obviously there were piles of shit but maybe if only because of the sheer volume of platform game production, soem great games have come out that pushed their console rivals into shame.
Platformers was the one genre that Amigas NEVER mastered. Mario, Sonic, these are the gods of platforms. The Amiga tried desperately, but never managed to produce any platformers that could be ranked better than "good".
The Amigas strongest point was that it had a lot of very original games (although at the time I remember saying the same thing about the Spectrum in comparison to the Amiga). It never really excelled in one genre likes PCs do now (FPS, RPG, RTS) it all was just a good "all rounder" IMHO
But not platformers.