Personally and subjectively I would be against an union.
The whole concept of the Israeli state was to be a homeland for jews regarldess of prior nationality and as such we have an openly and expressed bias for Jews. If you've had your foreskin cut off at age 8 days, regardless of where you are, you're elligible for an Israeli passport. Good luck acquiring one anyway else.
We're openly biased and encourage only Jewish immigration to Israel because this is the only place where the jewish community is a majority. We're not a big religion, we're not a big people and we're not a big country, which contributes to a somewhat repressed and cultural feeling of paranoia - if we're not the majority, the "goyim" will arrive and raze our villages and rape our women while shaving our beards and mocking our traditions.
Joining in the EU with the current demoraphic trends going the way they're going will be akin of the Israeli government stepping into an Arab league - the Arab and Muslim population of the EU is only going one way, and that's up.
There's no point in denying it since there has been a rapidly increasing trend of extremist parties leaning more towards xenophobia than towards acceptance and the European welfare state is being reformed in ways that may require structural changes not applicable to an openly-racist state such as Israel.
The European Union thus presents several challenges the Israeli people should not have to confront - first and foremost, the "Lost tribe" dillema. If tomorrow we were to discover a tribe of Jews in Ethiopia, at the current political situation we'd be free to do as we please and bring them into Israel at the expense of any other immigrant we choose. Under the EU, economical and political factors would influence our decision, and thus the establishment of the "Home for all Jews" would basically become morally bankrupt. How can we call ourselves an open haven for all Jews when we have to ask the French if they'd kindly encourage some of their richest memebers of society to uproot and move over?
A second problematic issue would be that of inadecuate changes to conform with the EU's demands. In the case of Turkey, the military was asked to stop being a major influence in the life of the country. Politically speaking, this is a true and absolute value which should be preserved - keep your guns unloaded and your watchmen at the enemy, not the government. culturally speaking? The military in turkey has stopped at least two violent revolutions by extremists and has stopped Turkey from slipping into a Islamo-facist state numerous times, and in fact it has even contributed to the existance of modern day Turkey. Israel also has several important cultural-specific traits which do not conform with European mentality and logic - we're not a logical people, we're extremely paranoid and sensitive. Asking us to implement some changes "because it should be done" is akin to barking orders in English to an Australian bushman - we just don't speak the same cultural language. Everyone who's ever been here is impressed, for better and worse, from our ability to jury-rig everything - it's gotten to the point a while back we manufactured cars out of fiberglass. Even though that experiment failed (mainly because camels would eat the chassis. true story.), the Israeli mentality of sticking things together with duct tape and a rubber band and praying it'll work is something which goes from as low as fixing engine parts to as high as political parties - this is the only country in the world that had no functional government because the leader of the oposition party refused to enter negotations unless he was offered the title of "Vice-Acting Prime Minister", meaning that if the PM and his replacing minister both got killed he'd replace them. We fix everything with patches and live in a reality where long term plans are 4-hours long.
A third major point of difference between us is based on our highly militaristic society. We've been involved in every major type of armed conflict since 1948, and have even pioneered new forms of warfare. The army and Ministry of Defense employs, directly and indirectly, more than 10% of our population at any given time. Every male and female over 18 have fired M-16 rifles and about half of the male population of this country is walking around carrying 3 years of combat service in crap places such as Gaza, with a noticeable number having been shot at a very large ammount of times. We're not a peaceful people because we haven't had a peaceful experience. We're militartistic, we live on our sword and we're very, very tough on the outside. There are so many automatic rifles on the streets of this country that NRA activists would be reduced into babbling incoherent morons at the sight of a train on Sunday. Our basic mentality is not Swiss and German, our basic mentality is Middle Eastern. We don't have the army as a means of assistance for population in trouble and as a national duty meant to give back to the country and society - we have the army because we need to make things explode and certain people need to be kept out in order to ensure that we live long enough as a country to develop a Swiss and German mentality...
My personal opinion is that we should engage in active trade, but not in active union. There is nothing to be gained except headaches. We Israelis would not tread lightly on the interal politics of the EU and we'd cause more trouble than we're worth, and the EU doesn't really need a bunch of whiney, militaristic pseudo-macho types giving them guilt trips over what happened 60 years ago. Most Israelis want the European trade-option as a means of exporting technology and importing goods. Most Euroepans want the Israelis to remain a harmless little sliver of land out of the way of the world. This is the optimal status quo - close friends, but not fuc|<buddies.