Good question. This is so difficult because the parties are such diametric opposites and the best for me would be one in between (I have always voted Lib Dem simply because it is either Lib Dem or Labour here but I don't know if I would vote that way again).
For me Labour are the party of mass immigration, huge house price costs, no social housing being built in 13 years, mass expansion of the public sector and lowering of standards, PFI contacts, selling gold at ridiculously low prices, dubious wars in Iraq and Afghanistan, throwing money at people in the hope that they will vote for you, mass expansion of the welfare state so that equality of outcome rather than equality of opportunity reigns and we have people who have never bothered getting the same amount of money as people who have always worked just because they have chosen to have loads of children. I feel like Labour are fake and hypocrites.
For me the Tories are the arrogant party of the rich, bankers, big business. I associate them with making the economy even worse by getting the poor to take on lots more debt, making house prices even more ridiculous than under Labour, not building any homes and purposely squeezing supply to increase house prices, not making work pay, tinkering around the edges, allow billion pound corporations to pay no to little tax, tax avoidance on mass, mass immigration, destroying the NHS, continuing many of Labour's failed policies, using spin to sell stories, not listening to the electorate, not giving the electorate a referendum, privatizing everything, just generally being nasty cliched cunts.
For me the Lib Dems are totally ineffective, useless, liars who reneged on all their promises (tuition fees), vote against things that would help the people they claim to represent, Clegg is a multimillionaire who wants tax payers money to pay for his ideals whilst he avoids tax, total hypocrite.
So, to sum up. All the parties are rubbish. I might vote Green but I disagree with them about so many things too. Maybe I just won't vote, but that's awful isn't it.