just thought i'd weigh in, but it's two different eras, it's impossible to compare. It's like comparing Wilt Chamberlain to Shaq - on one hand wilt dominated stats wise much more than shaq, but on the other the competition is much harder now with guys of more height, than what was around back in the day. Does that make Shaq better than Wilt or vice versa? No because neither was given the same opportunities as the other or same opponents as the other.
Same with Lee and Arnold, Arnold's physique was built for the judging style of that era, Lee's is built for the judging style of this era, and example being legs are a much more important part than they were back then, same with shredded glutes and hams.
It's pretty pointless IMO to even bother arguing about comparing them just accept that both have great physiques for their respective eras and leave it at that. You would be much better off comparing Lee to a modern day counterpart and Arnold to one of his era.