Election TV debate: Clash over Scots cash claim
The SNP leader has hit back at claims that too much cash "comes over Hadrian's wall" during the ITV leaders' debate.
UKIP leader Nigel Farage had said tax payers in England were "cheesed off" with the amount of public money that goes to Scotland.
But Nicola Sturgeon said Scots had paid more tax per head of population every year for the past 34 years.
It was the only time Prime Minister David Cameron and Labour leader Ed Miliband will appear together on TV ahead of the general election on 7 May.
Mr Cameron said the Conservatives' economic plan was working, adding: "Let's not go back to square one, Britain can do so much better than that."
Mr Miliband repeatedly described what he would do "if I am prime minister", in raising the minimum wage, banning exploitative zero-hours contracts and "rescuing our NHS"
Liberal Democrat leader Nick Clegg also took part in Thursday evening's debate, along with Plaid Cymru leader Leanne Wood and the Green Party's Natalie Bennett.
What the polls said
A YouGov poll of 1,100 people gave a clear victory to Ms Sturgeon, with 28%, followed by Mr Farage on 20%, Mr Cameron on 18%, Mr Miliband on 15%, Mr Clegg on 10%, Ms Bennett on 5% and Ms Wood on 4%.
But a ComRes poll for ITV made it a dead heat between Mr Cameron, Mr Miliband, Mr Farage and Ms Sturgeon, although Mr Cameron came out on top on the question of who was most capable of leading the country.
Mr Miliband was judged best performer in an ICM poll for the Guardian, taking 25% of support, just ahead of Mr Cameron on 24%. Nigel Farage was on 19%, Nicola Sturgeon on 17%, Nick Clegg on 9%.
A Survation poll for the Daily Mirror also put the Tory and Labour leaders neck and neck on 25%, with Mr Farage on 24%, Ms Sturgeon 15%, Mr Clegg 6%, Ms Bennett 3% and Ms Wood 2%.
Asked to give leaders marks out of 10 - by YouGov for the Times - the scores were: Ms Sturgeon 6.7, Mr Miliband and Mr Cameron 5.9, Mr Clegg and Mr Farage 5.5.
Ms Sturgeon began by stating the SNP - which polls have suggested is on course to return a record number of MPs to Westminster - would always "stand up for Scotland", but wanted to offer "friendship" to the peoples of England, Wales and Northern Ireland and would "help to bring about change for you too".
Mr Farage, however, claimed "canny Scots" had negotiated a better deal than other parts of the UK when the Barnett formula - which determines how public money is distributed - was created.
He said: "This all has to be rebalanced because frankly English taxpayers are a bit cheesed off with so much of their money going over Hadrian's wall, giving people no prescription charges and no university tuition."
Ms Sturgeon told him Scots had "paid more tax per head of population in every single year for the last 34 years".
In the television debate, Ms Sturgeon also hit out at the prime minister by arguing that the UK government could not cut its way out of a deficit, and insisted the NHS was the "most precious" public service the nation has".
In an apparent attempt to pitch the election as a straight choice between himself and Mr Miliband, the prime minister told the debate audience: "The choice at this election is sticking with a plan that is working or going back to the debt, taxes, borrowing and spending that got us in this mess in the first place. I say let's not go back to square one. Britain can do so much better than that."
Mr Cameron added: "The problem - and the real choice - is with Ed Miliband, who still thinks the last government didn't tax too much and borrow too much."
But Mr Miliband accused Mr Cameron of wanting to talk about the past rather than the future and said: "Some people will tell you that this is as good as it gets for Britain. I say Britain can do so much better than it has done over the last five years."
Iain Watson, BBC political correspondent
There could have been no better image of the changing political landscape of Britain.
While 50 years ago two parties took almost every vote between them, and just five years ago viewers of the TV debates might well have thought the era of three-party politics was permanent, this time there were seven politicians on stage. And three were women.
The SNP's Nicola Sturgeon dressed boldly in red - perhaps to underline her determination to supplant Labour as the main party in Scotland. And she derided the "old boys' network" in SW1.
The prime minister was introduced last and it looked as though he found it difficult to keep a smile on his face for the time it took to welcome his six opponents.
He seemed to grow in confidence but was perhaps wondering initially why he was so insistent on broadening the field from the 2010 threesome.
You could almost believe the women on the panel - Natalie Bennett from the Greens, and Leanne Wood from Plaid Cymru, as well as Ms Sturgeon - had consulted each other over launching an early attack on the austerity advocated by the main Westminster parties.
Mr Miliband said Mr Cameron had marginalised Britain in Europe, and added: "I don't think our place lies outside the EU. I think that would be a disaster for jobs, a disaster for families and business."
The Labour leader also attacked his Liberal Democrat counterpart Mr Clegg for "betraying young people" over tuition fees.
In response, Mr Clegg attacked the Labour leader's "pious stance" and challenged Mr Miliband to apologise to the British public for "crashing the economy".
Mr Clegg directly challenged Mr Cameron over his decision not to ask the richest to pay more towards deficit reduction, but instead to impose "ideologically-driven cuts".
Responding to Mr Cameron's casting of the election as a choice between "competence and chaos", the Lib Dem leader urged him to "imagine the chaos in people's lives" caused by cuts in spending on health, schools and childcare.
The SNP later said it had gained 1,200 new members during the two-hour debate programme.
The party's deputy leader, Stewart Hosie MP, also said an average of the YouGov, ComRes and ICM polls which were released immediately after the debate suggested Ms Sturgeon had won, which Mr Hosie said showed how "strong and persuasive" she had been.
Scottish Labour leader Jim Murphy said the debate had "made crystal clear the choice facing Scots at the general election".
He said: "In the debate there were seven passionate speakers but only two potential prime ministers. There are lots of ways to protest against David Cameron but only one way to replace him."
UKIP's Scottish MEP David Coburn - in an interview with Radio Scotland's Good Morning Scotland programme - defended Mr Farage's comments from the television debate.
He said: "I think most reasonable Scots believe in the fair allocation of money. I think the SNP may make a big fuss about this but I think fair minded Scots like myself and everyone else believe we should give the English a reasonable deal too."