I like Chaos Knight best. Stun from 2-4 seconds, cooldown 9 sec. Blink strike every 5 sec, deals 120 dmg. Critical strike with 11% chance to do 3 times dmg. Ultimate - creates 3 illusions who deal full damage for 25 sec. He's made to kill heroes with no stun. I just own with that guy!
Night Stalker is pretty storng (especilly at night). I just owned one game with him, I was beyond godlike with score 23-4. Had Divine Rapier at the half of the game with score 14-4, didn't die to the end when I got it.