I know that Turkey does have a hard time joining. The problem is Islamophobia. Turkey has been the longest attached country to the EU, but the seculars who ruled that country weren't able to achieve it and the Islamic ruling party now had set Europe as their big goal in order to turn Turkey into a true democracy and not a military appendix. Problem is that Europe's Christian democrats have problems accepting Muslim democrats. Don't ask me why. For these people the boundary of Europe is somewhere west of Ukraine and all east is Asia. Yes, they are a very important component of most European democracies and the are often the less worse choice compared to the nationalists that would eliminate the Islamic footprint in Europe. Part of their argument, shared by a large part of the population, is that Islam has no historical roots in Europe (don't try to argue with them about European history, they have a unshakeable brief education through Bild&Sun and the movies). On the other hand the Islamic party in Turkey are possibly not the most democratic guys, but what would you expect in a country with so frequent military take-overs? The nail in Islamic EU membership is the dire situation of Christians in Muslim countries. In Turkey the Christians face a number of religion related unequal rights for example and social inequality as well as death for converts from Islam to Christianity (while in Europe converts to islam can continue to live their live, but might face some social problems if pushing their religious identity signs in public). That's part of the larger plight of Christians in Muslim lands. The important side of the Turkish Islamic democrats is how they transformed the state, the society, boosted the economy and how they reached out to their Muslim brothers after Europe clearly gave them not a fair chance.
for centurys the Europeans lived under the threat of the once powerful Ottoman Empire, at their doorstep once amassed massive Turkish armys and they did suceed, the memorys are still fresh in the minds of the Europeans
also Turkeys is a powerful country, it has military service, and can call in 1 million men for war,and historically in wars from Korea (for which they were granted Nato membership) todays Afghanistan has shown to be true professional soldiers
in addition EU is big muslim majority country, EU is already worried about muslims in Europe, if Turkey joins then muslims population will go from around 3% to in EU to 15% in EU, that is something that EU cant have
for Turkey they dont give 2 hoots about EU, they no longer care about joing EU, cus when they wanted to join, when it was needed and when they asked for it they didnt get it, now Turkey is expanding economy 6-7% and has many technologys and good things it can give Europe during recession
in entire muslim world everyone has respect for Turkey, cus they are the most developed muslims nation, recently they send first Turkish airlines to Somalia and help many muslim nations, on Eastern Turkey many factorys are making goods for Iraq and Iran, thery support projects in infrastructure in all arab nations
today Turkey no longer needs EU, EU needs Turkey, when France passed resolution to recognise Armenian Genocide it was Turkey who put sanctions on French, Turkish threaten to ban imports and kick French backside in trade if they made such a mistake, this is a reverse from a few years ago when EU used to put sanctions on Eastern nations
times have changed and they are going to change even more, East is rising, you can say Turkey is the China of this region