You're smoking something. There's no way in hell his arms are the best.
Darrem Charles
Ronnie Coleman
Phil Heath
Arnold
Robbie Robinson
Yes they are the best.
All the men you list are great but they have flaws:
Darrem charles - no forearms to speak of and high muscle attachments
Ronnie coleman - biceps overshadow triceps (although his detail is unmatched)
Phil Heath - almost as good, just not quite as good as lee's
Arnold - are you kidding me? Biceps completely disproportional to forearms and triceps. Probably the worst on your list.
Robbie - high forearm attachments, monster peak tho!