Arc blade is a close second, and bladedancer my favorite class overall by far. I love the animation, the air dashing, the 3rd person view, and the rare, tense, Arc Blade vs. Arc Blade fights.
However, and I know this will be sort of an ironic complaint as I know how ignoble it feels to be killed by the Blade, but I dislike how it feels to roll up on a voidwalker or striker and slice->immediate death from nova bomb/fist of havoc. it's an at-least-once-per-match thing. I really need to improve my play to recognize the flashing level number on spec better. but I just really hate that feeling of getting hard countered rock-paper-scissors style and completely wasting my super.
the above classes don't react the same way to a sunsinger in my play so far. It isn't as panic-inducing in my target, but that's just fine for me... and I won plenty of 2v1s and even a couple 3v1s last night, and this is without even having everything unlocked.
I chased a guy out of B capture point last night on Bastion. He came in through the chokepoint door, saw me blade dancing, turned right around and ran out. He was on his sparrow and gone. My last slice literally was within 6 feet of the back of his sparrowa s he sped off.
It reminded me of the Simpsons grandpa walks in then walks out gif. He was just like, Nope. Smart man whoever he was.