I've seen more Bruce Willis movies (42) than I have movies of any other actor. The next closest is Gene Hackman at 33. Bruce Willis is one of those actors whose movies I will see just because he's in them, and although they are seldom great, they are also seldom terrible. Blind Date (1987) is a glaring exception.
Below I list Willis's ten roles that I have most enjoyed. They are almost entirely action roles. It's hard to appreciate him in non-action movies, like The Story of Us (1999) or Breakfast of Champions (also 1999), because those movies aren't fun to watch. I also omit a few iconic roles because it's been so long since I've seen them, I don't recall whether he was actually good in them: Look Who's Talking (1989) and Pulp Fiction (1994)
10. Lucky Number Slevin (2006) — Mr. Goodkat
Willis is a hitman, but is more likable than his turn in The Jackal (1997). I enjoy competent characters; characters who are experts in some field, and have no trouble dispatching common troubles. In action movies, this usually means someone who is good at evading, fighting, or killing. All three are fun to watch given the right tone.
9. Tears of the Sun (2003) — Lieutenant A.K. Waters
Willis is a grizzled soldier, leading an elite team and a band of refugees through a hostile jungle. He brings to bear the same determination we saw in Armageddon (1998) ("We'll get the job done"), but in a movie that's actually good.
8. 12 Monkeys (1996) — James Cole
Willis's role is very spastic in this time-traveling movie. We see mostly one continuous thread, from his perspective, but time travel leaves him discombobulated. He does a good job of being the everyman in an extreme situation. He channels Kyle Reese without trying to one-up him.
7. Hostage (2005) — Jeff Talley
The anti-competancy movie. Willis had a meltdown as an inner-city cop, and so has retired to a rich community where he's an unneeded sheriff. A hostage situation ensnares him, but does he try to save the day on his own? No. He calls for help. All sorts of help. He has no delusions about his own abilities. More than any other role I've seen him in I believe he feels fear when he's in a dangerous situation.
6. Hudson Hawk (1991) — Hudson Hawk
If you haven't seen this movie, do so while you can, as video store clerks across the country have orders to destroy this movie on sight. It's most famous for being a flop, though it's better than so much trash that succeeds. The film is bizarre. Willis plays a silly cat burglar who gets roped into an elaborate theft involving artifacts from Leonardo DaVinci. All the leads are extreme and absurd.
5. The Sixth Sense (1999) — Dr. Malcolm Crowe
Willis at his most subdued...
4. Unbreakable (2000) — David Dunn
...until this turn. Here he conveys the pent up man, the man who feels like a nobody and wonders where he went wrong. The man who's losing his wife, but doesn't know how to pull her back. In most his movies, Willis looks like he could snap necks; here he seems damaged and sensitive.
3. The Siege (1998) — Major General William Deveraux
One of few villainous roles for Willis, but a believable one. Instead of being a warmonger, Willis's General is a servant of the people, more aware than anyone of the violent skill set at his command, and reluctant to enter the conflict. But when his hand is forced (or did he manipulate events?), he fulfills his duty, treating New York City as hostile territory. He is intimidating and sincere.
2. Last Man Standing (1996) — John Smith
Willis at his most competent. He doesn't back down from bullies, preferring instead to shoot them and take their jobs. Catering to both sides of a mob war, Willis allies himself against whichever side is most in need of attrition. He can shoot with a broken windshield or a broken hand; while having sex or taking a bath. He's kind to strangers, enjoys whiskey and long walks in the desert, and generously donates bullets to anyone who has it coming (and we all have it coming).
1. Die Hard (1988) — Officer John McClane
His masterful blend of comedy and action. Willis has become so iconic as a weathered war veteran that his few attempts at comedy seem out of character now. But back in the day he could kill and quip with the best of them. Schwarzenegger pins someone to the wall with a machete and says, "Stick around." Willis sends a body downstairs in an elevator, having written on the dead terrorist's sweatshirt, "Now I have a machine gun. Ho ho ho." Like Spider-Man, he uses humor to hide his own fear, but also to infuriate and disarm his opponents. Yes, he's a super cop, but he's convincing as someone who must think through the situation, staying alive long enough to ascertain the villain's ultimate agenda. Oh, and he does it all barefoot.