For me it's: Anthony Hopkins Robert De Niro Tom Hanks Robbie Williams John Travolta Nicolas Cage They are really great actors.
Well, the question wasn't about who's a great actor, though, but about which actors avoid ending up in bad films.
Travolta, for example, has made
Mad City,
Basic,
Look Who's Talking Too,
Look Who's Talking Now, and one of the most mockable films of all time,
Battlefield Earth.
Cage has had the misfortune of appearing in so many bad films that I actually had to defend him in another thread from someone who claimed he never makes any good ones. Among his alleged missteps are
Next,
Windtalkers,
Captain Corelli's Mandolin,
Face/Off and especially
The Wicker Man.
And, alas, while Robert De Niro is a fantastic actor who has found his way into some of the best movies of the last few decades, he isn't very choosy. In fact, another member mentioned De Niro in this very thread back in June (page 1) and both
myself and
Holden (in consecutive posts) enumerated some of the many, many poor films he's been in.
Anthony Hopkins is a better choice, but far from perfect. He was in both
Alexander and
Instinct, two huge bombs, and
Bad Company. But I agree his track record is quite good overall.
And obviously I think Hanks is a pretty good choice, too.