As with many debates on here, I come to different conclusions depending on what aspect I'm looking at:

As an internationalist, I think we should stay in
As a believer in the free market, I think we should leave
As a pragmatist, we should stay in
Democratically I see arguments either way - the EU parliament is elected, but local issues have no way to be taken into account give the scale of the thing
Legally, I quite like having a legal framework that prevents power being misused by UK parliament. And things like the EU working time directive, and paternity leave are good examples of progressive policies
As a radical, we should leave and forge our own identity, rather than being one of the many

Which leads me to a mildly pro-European stance, but I wouldn't be offended if we decide to leave. I'm surprised by the certainty with which some people (mainly politicians but also people on here) can make claims about what will happen. The truth is no-one can know, it's all conjecture.

The other thing that comes through quite strongly, is how little difference it will make. If we want to trade in the same way with the EU after leaving, we'll have to abide by their rules and continue to pay in. Yes, it will be less of their rules, and we'll have to pay in less. But it's not the bold "sailing our own course" that some people are heralding.