Polly Toynbee: Nick Clegg, as last time, was well ahead

Could he do it again? It was for Nick Clegg to lose – and how desperately the Conservatives needed him to fall on his face. Those rabid press attacks only seemed to put the wind was in his sails. Nick Clegg showed it didn't matter who stood where, except on the issues. He seized the high ground and commanded the argument.

He outdoes the others in sincerity by refusing to stoop to seize any vote. He stood his perilous ground on an amnesty for immigrants, while both the others were shameless. His other danger zone was Europe: what bit of him was British, asked the Mail? But Cameron never laid a euro-glove on him. Instead Cameron was put firmly back into his little Englander box in a pincer movement from Brown and Clegg together, leaving him sounding uncomfortably old-fashioned and dogmatic. On Trident, Clegg beat off attack from both sides.

Gordon Brown was better than before, though his opening "like me or not" gambit was embarrassing to watch. He made his strong anti-Tory economic case with an authority that did him good.

Why does Cameron fail to shine? Because the sincerity deficit shows, with slogans, mantras and an advertising man's repetitions. Up against the earnest Nick and sobersides Gordon, Cameron sounds oddly fake. Television is mercilessly revealing, and lack of conviction tells. He needed to retake command, but couldn't quite. A coalition with Clegg? It looked unlikely.

Verdict: Clegg, as last time, was well ahead

Seumas Milne: Brown and Cameron couldn't catch up with Clegg

Gordon Brown and David Cameron had both picked up some of the tricks that helped Nick Clegg turn the election campaign on its head in last week's debate. "Get real," Brown told the Liberal Democrat upstart. The other two were guilty of "the same old politics", David Cameron insisted, echoing Clegg's earlier winning theme. Both did better at looking human.

But when it came to what you might imagine would be the foreign policy centrepiece – Afghanistan and the war on terror – the large majority in Britain who oppose the war didn't get a look in. All three leaders formed a common front against their voters who want the troops brought home – and behind the transparent fiction that the Afghan occupation is keeping Britain safe from terrorism.

We even had an "I agree with Gordon" from Cameron on nuclear weapons. Clegg faced down the absurd attempt to paint any questioning of Trident's replacement by raising it himself. Perhaps fear of being portrayed as "weak" on security meant the Lib Dem leader failed to ram home his advantage on the New Labour-Conservative backed Iraq catastrophe – he only mentioned it once in passing.

But quite who Brown thought he was appealing to by accusing Clegg of "anti-Americanism", or Cameron of "anti-Europeanism" for that matter, was unclear. At one point Brown seemed to be threatening a new attack on Somalia and Yemen, apparently oblivious to the disastrous reputation of the terror wars unleashed by his predecessor and George Bush.

And how many of those watching could really disagree with Clegg when he countered that the special relationship with the US "shouldn't be a one-way street", nor Britain be "at the beck and call of anyone else"? The two main party leaders still seemed to be trying to catch up with Clegg.

Timothy Garton Ash: There was one clear winner – us

The man in the middle more than held his own. Nick Clegg knows what he is talking about when it comes to international affairs, and it showed. At moments, as he spoke of his experience negotiating with China and Russia, he seemed a commanding presence, batting away those inexperienced pretenders to left and right. On Europe, his great test, he survived. No more, but also no less.

Against that vaguely British Airways stage set, David Cameron will have won back some straying Tory voters by blowing the patriotic trumpet. He rarely if ever commanded the scene. When he tried to show fire, he sounded petulant. This is just not his genre. And he talked calmly about the prospect of a hung parliament – which makes it more likely.

"Like me or not," said Gordon Brown, implying we might not. He laboriously quipped about the other two looking like his children squabbling at bathtime. "David is anti-European, Nick is anti-American" he said, in an obviously prepped line. And later: "David's a risk to our economy, Nick's a risk to our security." Got to be even-handed between the children. It didn't convince. If you want the liberal centre-left, why not go for the fresh one?

There was one clear winner: us. This is becoming a good way to make our choice, not mere Simon Cowellism. The prepared soundbites generally fall flat. We get some of the real arguments. British elections will never be the same again. In just a fortnight, Britain may never be the same again.

Henry Porter: Gordon Brown is out of the TV race

We now know for certain that the leaders' debates have enriched the general election. Still, I do have doubts about the way debate and indeed the whole campaign falls into a hush between the TV events, as parties digest the results of one debate and plan for next.

The Sky debate was not as good as the first debate run by ITV in Manchester. Several questions allowed the three candidates to reach a consensus and there was too much repetition in the themes, allowing the three leaders to come out with much the same answers as they provided last week, sometimes using exactly the same phrases. The chairmanship of Adam Boulton lacked Alistair Stewart's edge.

As to the three men, Gordon Brown's performance did not pick up from his outing last week: he began to look more and more like the past. He had little that was new to say and appeared uncomfortable when David Cameron challenged him to withdraw the leaflets that Cameron alleged lied about Conservative policy. The prime minister looked tired and occasionally I found my finger twitching on the remote, as it does when I want to avoid an embarrassing scene on TV.

Cameron did much better this week with a more aggressive and certain performance, which seemed to relish his lack of likely alliance partners on the platform. But at the same time he seemed a lot less likable, and at times looked the "good butcher", which is how Asquith described the qualities of a tough prime minister. Staring straight at the camera and appealing to the TV audience rather than the people in the studio worked for him, but you saw the aggression there and I did not respond well when he used the word "lie".

Nick Clegg did much better in the foreign affairs section of the debate than I had expected and he succeeded in holding the ring, as he did last week, with a combination of good-natured frustration, which he does well, and a convincing desire to work with politicians of all parties. On the detail of policies he was good and consolidated the gains of last week's performance, though he clearly had much more to lose this time. Cameron and Clegg were neck-and-neck with Clegg a whisker ahead. Brown is out of the TV race.

• More Guardian election comment from Cif at the polls