Realistically as long as you don’t think Sakazuki, Shanks or Mihawk are the strongest of all time you’re unlikely to be disappointed in them. Shanks is the least likely to disappoint of this set but all will be fine.
Dragon, much as it pains me, could easily be a disappointment for some Luffy wank (or worse, fucking Sabo).
Everyone should invest in Blackbeard Pirate stocks now.
And like I said I just don’t think Imu’s even a fighter.