Just a simple poll, which enemy faction do you absolutely hate going up against?
For me, it's the cleaners. Nicking their tanks, seeing the jet of flame and knowing their about to 'take off' (as hilarious as that can be when it happens) doesn't quite make up for the flamethrowers, molotovs and guys with shields-and-fireaxes.
-
Doesn't matter the faction. Any of the units that rush you can go run off a skyscraper imo.