Right now I live in Germany. Don't go to Germany - the bureaucracy is absolutely @#@#$ crazy. Today I went to a lawyer and to AOK (German NHS), they said two contradicting things, the system is insanely complicated, I waste SO much time an energy, people usually don't speak English and are absolutely NOT proactive, if anything happens they will not provide you solutions, and since they have a particular understanding of "professionalism" they will not smile, which makes you feel you annoyed them, offended them etc. and you will ask your self: "have I done anything wrong?".
I lived in Denmark and Sweden before, in both 99% people speak English, system is clear, helpful, forgiving, supportive. Coding environment is rich, strong, creative and growing. It comes at a cost - taxation is merciless, but if you plan to have a family and like outdoors, Stockholm is the place to go. Working conditions, days off, healthcare, childcare, you name it, it's great. In Denmark I lived with a woman who had a rare lung desease, lymphangioleiomyomatosis, and was waiting for a transplantation (M., rest in peace), the state paid for everything, a cab came twice a month to take her to cinema or restaurant, she had an extremely expensive light oxygen machine with which she could go for a walk or take a shower like a human being. So it's really great.
Poland and UK I would not recommend because of the political situation there is not sane or predictable. But both have surprisingly low taxation, I ran a company for two years in Poland, costs are very low for a big European country with good developers (e.g. you pay flat 18% income tax + ~300euros social&health insurance) and you can get junior developers (I know about .NET C#, Sharepoint) working for you for 1000 euros a month, seniors for 2000-3000. And life is extremely cheap minimum wage is something like 400 euros a month. I did accounting myself, the tax authorities did not penalise me for making a lot of mistakes and being weeks late with paying VAT (!!!) or totally messing up with the tax declarations (confused net with gross income and costs calculations). Most of the paperwork is done online, accountant will take as little as 30 euros a month to take care of it for you. To get incorporated (ltd.) costs about 500 euros for the lawyer and then a bit more for accounting, but you (if I remember correctly) don't have to have any initial capital - marvelous! There are also companies that sell ltd's with good credit history, so you can also easily buy a dormant ltd. company without much paperwork and quickly get a credit/ apply for European funding.
But now they are messing up with the law so I'd be careful.
A lot of warm things I've heard about the Netherlands and I would consider Amsterdam for myself as the next stop. Same situation - good social support, very open and direct culture, sane and predictable state and rules of the game, great high-tech environment, everyone speaks English. Big minus - once you employ someone it is VERY difficult to get rid of the person. Workers protection is great for the employed, not so much for the entrepreneur.