I don't think one can objectively be best because they all serve different purposes.
The sai EM effect, the pincer charge move for heavy damage, etc.
That said... I can't bring myself to ever really use any of them. I love the full sword moveset too much even if most of the triangle button moves are less efficient than just square spam. Style is more important, of course!
Every once in a while I'll use Sam's blade for kicks or the FOX blade just to be silly but other than that I never use anything but the HF Blade.
That said, if I had to pick one I'd go with the Sai. The 'pull' move and the stun effect are both quite nice. After that the pincer for the charge move. The staff is cool looking but doesn't do all that much that the HF Blade can't already do for you with dashing square spam / square spam.
Though if I recall combining Ripper mode with the staff is actually pretty darn effective...
"The act of treachery is an art, but the traitor himself is a piece of ****." - Mike Tyson