Hung Parliament?

If there is a hung Parliament where the Liberal Democrats hold the balance of power... which of these three options would they prefer?

Work with the Conservatives under Cameron, or
Work with Labour under Brown, or
Work with Labour under another leader?

If it were to be the latter, and with the polls pointing towards a hung parliament, it could be said that a Liberal Democrat vote was a goodbye to Brown vote. How would that go down with the voters?

It makes one think.