teddy atlas is the best imo but not biased
The most bias is without a doubt was Merchant who hated defensive boxers with passion and it seems that influenced Lampley to do the same. Teddy Atlas is more objective but he rarely talks about the action like a pro.
Roy Jones usually talks up the favorite in the fight but his commentating is relevant and accurate. I do wish it wasnt too one-sided for one fighter though.
Al Bernstein and (once upon a time) Gil Clancy are the best and most consistent. Showtime usually hire very good commentators like Paulie or Tarver
The HBO squad. Mainly Jim Lampley and Max Kellerman.
Ward, Steward, Roy Jones jr, Max Kellerman
The most non bias boxing commentator that I know is Al Bernstien he has always just been a great commentator and rarely gets the credit he so rightfully deserves.
*Edit-I'm sorry since the question is asking the opposite of what I stated.
Jim Watt of Sky Sports usually bums the 'house fighter', and has awful scorecards.
Bob Sheridan and Larry Merchant.
all commentators are bias because they are paid to say the network want them to say...
People tend to say ignore the commentators surely they all can't be wrong who is the most consistent?