I like to think of myself as centrist... I usually support the major centrist party in Canada (the Liberals) though this time around I'm wavering between the Greens and the NDP (the social democracy party).
In principle I'm more of a social democrat, but in practice I try to avoid blindly dogmatic opinions by reading academic research on the subject in question; in the process, I sometimes find that the centrist or conservative position is better-aligned with the bulk of empirical findings.
However, I don't think it actually matters all that much who's elected, as right-wing governments often wind up leaving very 'left-wing' legacies and vica-versa. For some very brief examples, consider:
Menachem Begin - former PM of Israel; leader of the far-right Herut Party and ex-terrorist - returned the Sinai Peninsula (almost two-thirds of the land under Israeli control at the time) to Egypt in return for the historic peace treaty;
Richard Nixon - former US President; 'conservative' Republican - ended the Vietnam War, established diplomatic relations with communist China, and instituted wage and price controls across much of the economy;
Fernando Cardoso - former president of Brazil; avowed Marxist - sold off SOEs (state-owned companies), encouraged international trade and investment, and eliminated regulations; and (this one's my favourite):
Ronald Reagan! - former US President; demigod to the right wing of the right-wing Republican Party, and inspiration of the uber-conservative Tea Party! - left as his legacy a very soft foreign policy that favoured engagement and rapprochement with US enemies (at least in his second term; shades of Obama?); increased government spending (both in absolute terms and as a share of GDP); and a sky-high deficit. Reagan left a right-wing legacy as well (deregulation and lower tax rates for the upper brackets) but even there, government revenue (which in the US is mostly synonymous with tax revenue) as a percentage of GDP rose and he was outdone by Bill Clinton (a Democrat) in deregulation.