Most satisfying enemy encounters

[Lord Beautiful]

Fighting Nelo Angelo in Devil May Cry is endless fun.

 

[doctorvsmaster]

Running away from Nemesis in RE 3

 

[Earthbound]

Any single enemy encounter in Ninja Gaiden 2. Most of the time, all you leave behind you are bodies without heads or limbs as the bodies burst into flames and burn to ash. Yeah, that's always fun.