Clint Eastwood has a body of work that no other actor can currently get near. He's been a major star since the mid 60's and I could easily watch the three 'Dollar' films, Kelly's Heroes, Where Eagles Dare back to back and then move on to the Harry movies, Eiger Sanction etc.
Harrison Ford might be second although I really would only watch the first three Star Wars, first three Indys, Force 10 From Navarone and The Fugitive. I wouldn't be that keen on many of his other films.
Laurel and Hardy are a possibility as well although a lot of their stuff were 'shorts' if memory serves me right. I'm not sure they were all fully fledged films.
I have re-assessed Arnie in recent years and I barely rate his films at all now. He's got the first two Terminators and Predator. Other than that I'm not really interested in his stuff and think its pretty poor. Has anyone watched Commando recently? I loved that when I first saw it. Now its just horrendous. Its almost so bad its good.