Stay - Obvs. Anything else would be daft
The EU currently accounts for around 60% of our international trade and that is due to rise to 75% after TTIP is signed and the US (15% of our trade) joins along with the rest of NAFTA. We therefore have absolutely no choice but to make a trade deal with the EU.
If we want to trade with the EU, we will have to do so under the EU's terms - one it's key raisons d'etre is to give it clout in trade negotiations. Our best conceivable option would be a deal like Norway's. Norway currently has a higher compliance with EU rules and regulations than any other country - yes, including every EU country. It's also one of the biggest net contributors to the EU budget.
Why did the eejits say they want to leave the EU again ..?
The idea that we're so big and important the EU will have to give us some exceptional deal is so much baloney: we may be the world's 5th biggest economy now but we indisputably won't by the time we leave. Scotland and her oil will be long gone and the Welsh - if they have any sense at all - will be close behind.
Common sense would dictate that Northern Ireland would also leave the UK and unite with Eire but of course, this is NI: given they almost went back to war last year over a rag on a stick (sorry, flag over a council building), it would be a pretty fair assumption that one side insisting the country sign an economic suicide pact with England would kick start the troubles again.
Then there's UKIP nonsense about returning to some mythical pre-EEC economic dominance. Complete and utter rubbish. Our economy enjoyed a brief uptick after WWII because the world was rebuilding and would buy anything. That was long over by the late 60s and unlike before the war, we no longer had the world's biggest empire that we could force to buy our goods.
What people appear to forget is that our pre-EEC position was on our knees begging the EEC to let us in - as we had been for much of the previous decade while de Gaulle delighted in telling us where to go. Does anyone really think Ted Heath got the deal he did negotiating from a position of strength? Our position was so weak, the EEC negotiators were taking the mickey, throwing in last minute changes just because they could.
The only thing that's changed is that the EU is way more powerful than it was then - and is about to be joined by the world's greatest economic power, the US of A.
Which I think leaves one argument the eejits make for leaving the EU: migration.
Here's a shocker: migration's actually really good for us. Even if you ignore the looming demographic crisis (remember that?), pretty much every serious study shows that immigration is good for the economy. Look at ours: we've had record EU immigration over the last 2 or 3 years and our growth has been among the highest of the developed countries and unemployment has been falling fast.
Then there's another short term benefit of EU migration: the effect on our current account deficit.
Our deficit means that on average, each non-immigrant costs the government £9,000 per year - i.e. the government pays out £9K more for us than it receives in tax from us.
Non-EU immigrants cost slightly more.
EU migrants though, are generally, young, well educated and hard working. Consequently, they actually CONTRIBUTE an average of £7,000 per person, i.e. they pay £7K more in taxes than they cost.
Given our current account deficit is one of the worst in the world - yes: it's now worse than the US, Greece, Spain or Eire - we can't afford not to have the EU migrants.
Staying in really is a no brainer - as just about every opponent admirably demonstrates (apart maybe from Boris, who is clearly putting self interest ahead of the country's interests - he's even said he wants to use an out vote to stay in but with a better deal - that deal being he gets to be PM, apparently).