Terminator, easy. Had Arnold's acting career never taken off, he'd still be looked back upon and laughed at because his acting was horrible. No one says that today. Arnold was a genius business wise and he was also very machiavellian about what he was willing to do which means that there have been rumors of him letting not only movie people but Joe Wieder before that have their fun with that legendary body. He seemed to be very, very shrewd and aggressive with his goals in America. He made Stallone into an enemy just to motivate his own ambitions and talked shit about him because there was a time when he wasn't in that league. Stallone made an admission in the recent netflix docu that Arnold was the better action star which hurts to hear because nothing that Arnold gave us rivals the Rocky character, at least to me.
But anyway, i'm getting way too into the shit, Arnold did struggle and he was not an actor but he was hardworking, disciplined and got the most out of what he had, any way he had to. His movies got better and better as his clout grew. By the 90's, Stallone was trying to keep up with his crappy sci-fi movies like Judge Dredd.