As a champion and world record holder in the mid-1990s, Obree caught the imagination with his home-made bicycle Old Faithful. Throughout his lifelong struggle with mental health, he has remained a quirky, relentlessly inventive sportsman, assembling bicycles in his kitchen from household objects. Then in 2012 he becomes obsessed with winning the World Human-Powered Speed Challenge at Battle Mountain, Nevada. For this, he builds a prone bike that fellow champ Chris Hoy names The Beastie, the faces a series of personal obstacles to take part in the 2013 competition.

Obree has terrific screen presence: a complex, lively man who refuses to limit himself to what's expected of him. He also seems addicted to the idea of winning, needing a goal to pursue at all times. Few athletes would attempt a world record at age 48, and yet he dives in headlong, despite suffering a physical setback that would ground someone half his age. He's ably supported by his two adult sons Jamie and Ewan and a group of fiercely loyal friends. And his inventiveness knows no bounds, as he tinkers with his bicycle right through the competition.

Intriguingly, the film never tries to explain Obree's unique situation, leaving tantalising comments dangling without analysis, such as when he mentions how he felt like he had a mental age of 13 when he got married, so didn't yet realise that he was gay. He is remarkably open about his feelings, from dark thoughts that led him to attempt suicide to jokes about cannibalising his washing machine for parts. His anger about rampant drug use in sport is palpable, as is his love of cycling across picturesque landscapes in Scotland or Nevada.

Filmmaker Street skilfully balances Obree's wacky antics with his dark bipolar condition. He also avoids digging too deep. Outside opinions are relevant and telling without becoming invasive. And Obree narrates the film with both self-awareness and self-deprecation (although his brogue sometimes obscures his words). As a result, the film is utterly riveting, both as a profile of an extraordinarily talented man and as a look at what it takes to be the best in the world.

With colourfully animated sequences by Bill Plympton, the film is Senko's personal quest to understand what happened to her formerly funny, loving dad Frank, who came from humble roots and treated everyone with respect. But this non-political Kennedy democrat's views shifted when he began listening to talk radio. Obviously, a move to the right isn't necessarily brainwashing, but Senko observes that if information goes in without being challenged or questioned, it narrows a person's horizons and can actually alter the brain's circuitry, changing basic beliefs.

Senko uses so many expert interviews that the film begins to feel rather academic. And she also has a tendency to dip into the same kind of fear-mongering that's seen on Fox News. But the details are fascinatingly well-documented, going back to the communist hysteria of the 1950s, then coherently tracing Republican Party efforts to crush every Democratic president since Johnson with coordinated media attacks. This includes claiming that there's a liberal media bias, which has never been true but creates a perceived need for an alternative voice.

Roger Ailes has said that "people are lazy and want someone else to do the thinking for them", so it's hardly surprising that he's now CEO of Fox News. As a Nixon PR guru in the 1960s, he started a project to nudge public opinion to the right, shifting sympathies from champions of the people to big corporations and millionaires while convincing people to vote against their moral principles. This required the repeal of the Fairness Doctrine (Reagan saw to that) so journalists could say what they wanted, tapping into resentments and insecurities.

Senko traces this with striking clarity, even as it begins to sound like a conspiracy theory. But in her father, she has vividly personal proof, tracing his shift from life of the party to a mean, angry man who alienated his family by forwarding hateful email messages. Her final masterstroke is to wean him from this media and see what happens. And this makes the film both chilling and important, exposing the "noise machine" that obscures real values and truth with fear and blame. And it also shows how easy - and urgent - it is to reverse this indoctrination with the facts.

In a conversational voiceover, filmmaker Cousins speaks with an old woman (Bereen) who says she is Belfast itself, 10,000 years old. On-screen, she guides the camera to places with visual impact or historical importance, continually returning to the city's origins at the mouth of a river, where sweet fresh water runs into the salty sea. Sweet and salt, light and dark, male and female, Catholic and Protestant. It's a city that embraces its contradictions, both joyful and tragic. And the symbolic funeral of the Last Bigot (Perry) in town signifies hope for the future.

Photographed gorgeously by Christopher Doyle, the film weaves in historic clips including home movies and newsreels from the past century to illustrate the central idea. Meanwhile, Bereen shares a series of detailed anecdotes that portray the city's hideous violence and generous spirit. Sometimes this feels a bit too calculated, with its series of points and counterpoints, beauty and ugliness. And aside from personal memories, there isn't much real information here to make Belfast look different from other cities that have seen violence.

But the approach to the Troubles is a new one, observing it in a matter-of-fact way without any political angle. This vividly captures the way a city might "feel" about the turmoil of its residents, although it somewhat mutes the inflamed passions of those caught up in the middle of it. Scenes of hotspots of violence are shown in the present day, with scars in the shape of giant walls or failed housing estates. This adds to the film's overwhelmingly melancholic tone.

It's intriguing that Cousins lived in Belfast as a child, but his family fled the violence and now he returns as a prodigal son. His attempts to understand the meaning of the place are powerful, and the film's combination of imagery and music (by David Holmes) is beautifully textured. But the best scenes are the lively banter of the people, such as a riotously hilarious conversation between foul-mouthed pensioners Keen and Bell. More of this might have given the film a stronger kick.

Born in 1946, Mapplethorpe was a lively kid who showed early artistic talents, diving into the New York art scene with his girlfriend Patti Smith in the 1960s. He came to photography later, initially thinking that it wasn't an artform then proving otherwise with boldly truthful images from his own life, including his obsession with sadomasochism, flowers, muscle-women and black men. He forced the world to reconsider the impact of photography, and courted controversy even after his death at age 42 when the US government tried to censor his work.

Bailey and Barbato assemble this film beautifully, mixing in audio interviews with Mapplethorpe and Smith, comments from friends and colleagues, and a wealth of private footage and snapshots. Plus, of course, the photographs themselves. Interviews with his siblings (Edward and Nancy) offer telling insights into how Mapplethorpe developed from a quirky child into an almost mythical artist, while his models, collaborators and lovers all share memories that are resonant and powerful.

Clearly, Mapplethorpe was a man with his own set of inner demons, like everyone else on earth, but as an artist he was willing to dive in and explore them, dragging them out into the light to reveal his inner self through his work. This is a striking exploration of why an artist isn't properly appreciated during his or her lifetime. And also why the most provocative works of art spark the strongest reaction from those who are touched perhaps a bit too deeply by what's on display.

Thankfully, Bailey and Barbato refuse to let this film turn into a rant against censorship, instead showing the images over and over, which means that they cease to be confrontational and reveal their innate beauty. For some people, Mapplethorpe's most explicit photos are simply too strong to ever be considered artistic, but this expertly assembled film proves that they must be taken seriously. As one of the first artist photographers, Mapplethorpe changed the art world forever. And his unflinching depictions of sexuality bravely brought truth out of the shadows.