Nothing in British festivals can match the main stage backdrop at Green Man: the kind of mountain ridge that Lord of the Rings characters gaze at in worry. The tradeoff is often Welsh rain, but this year, with the sun out – and a bill stacked with smart, warm, confident artists – it has a fair claim to be Britain’s best festival, full stop.

The highest point is Big Thief, who subvert the laws of festival headline sets by filling two-thirds of theirs with unheard new material. From brawny country rock to pristine ballads and – on the all-consuming groove of Hand Through Table – headnodding post-rock, the new songs’ tonal range is huge. They’re all received like old classics; closer Incomprehensible earns a huge singalong despite no one having heard it before. The band recently replaced a departing bassist and added a percussionist, a doubling-down of the rhythm section that gives tracks such as Simulation Swarm greater heft than before, but Adrianne Lenker still dominates out front, whether shredding noisy solos or singing over acoustic guitar to silent reverence.

They cap a stellar Saturday, opened by electropopper Lynks, who apologises to the numerous children in the crowd before rapping “I’m on the DLR on my way to fuck a stranger”. Tinariwen and Devendra Banhart each bob along on undulating grooves, the latter dropping in covers of Aaliyah and Madonna, while US rockers Wednesday out-shred even Lenker, as Karly Hartzman delivers cathartic screams in Bull Believer (here they dedicate its rage towards the US in supplying arms to Israel). Lonnie Holley has an equally astonishing voice, whether singing over ambient blues and choppier, funkier numbers, or delivering wisdom as he confronts the biggest existential mysteries: “We don’t know what makes us humans … But what keeps us humans?”

Throughout the weekend the big Far Out tent hosts some euphorically received crowd-pleasers – disco-funk from Ibibio Sound Machine, Irish traditional reels from the Mary Wallopers – as well as an astonishing Blonde Redhead set, with a vast art-rock sound emerging from just three people, surging on a dark, powerful swell of rhythm. Joy Orbison’s DJ set is also full of off-kilter funk – though he rightly indulges in a megamix of versions of the year’s defining underground hit, his own Flight FM.

At the Walled Garden, Porridge Radio play a typically impassioned secret set, Jess Williamson channels dolorous Dolly Parton and Fabiana Palladino’s wonderfully sophisticated 80s pop makes it feel more wine bar than country paddock. Over in the verdant dell of the Rising stage, four-piece the New Eves sing about the elements and duly conjure a tiny flurry of rain: no Venn diagram can contain their blend of English folk with interpretive dance, Raincoats-style singing and a curious arsenal of instruments from squeezebox to flute. Another quartet of women, air-punchingly fun garage rockers Loose Articles, encapsulate festival priorities with a song “about drinking a beer with your pals instead of having a shit shag”.

There are a couple of stinkers back to back on the main stage on Friday: avant-dance-rock ensemble Mount Kimbie play an utterly inconsequential set of vibes-over-content, their rote singing and weak patter shown up all the more by guest star King Krule who suddenly lifts the entire endeavour with his distinctive, ruminating voice. Headlining is Jon Hopkins, who brings his skill for high-grade sound design, with bass notes like orbs of air hurled at your chest. But he plays techno as if he learned it in a classroom, rather than from being embedded in the culture itself: any funk is overworked and ersatz, while the electro-symphonics are terribly lofty and self-important, as if he’s deigned to bring it down from the mountain behind him.

Fortunately, Sherelle’s subsequent typically high tempo DJ set is quite the opposite, with jungle, footwork, hardcore and more: even when playing ghetto house at its most unyielding, it’s profoundly danceable and generous. The latter feeling is what comes to define Green Man. Amid his sensational closing headline set, its rhythmically daring tracks suffused with a kind of secular gospel benediction, Sampha tells the crowd “you guys feel so open”: indeed, this festival is full of artists giving everything they have to audiences who receive it in the same spirit.