I use my experiences and knowledge as a "recovering" lawyer to access my vast global network of colleagues to connect people with great career and business opportunities all over the world. I help start-ups navigate the world of Canadian immigration laws to bring required key personnel into Canada to help grow their start-up, when required.
The answer will depend on various factors, including the structure of the company, your position/title/duties, your shares, remuneration you are receiving (salary by T-4, contractor (no T-4), dividends, etc.), does the company employee Canadians or permanent residents, profitability of the company, your English test results from a standardized testing organization, e.g. IELTS, CELPIP.
A lot of changes have occurred to the management of most immigration applications (Express Entry introduced in January 2015), creating a more competitive and fast paced immigration process.
http://www.cic.gc.ca/english/immigrate/express/express-entry.asp
The Ontario Opportunities (Provincial Nominee Program) program remains a very good option for recent graduates of Ontario colleges/universities and if you hire an experienced immigration lawyer to strategize and plan the best pathway to immigration, using your company as a catalyst/springboard (applying for Employer Pre-Screen of a Job Offer), you have a high likelihood of success in gaining permanent residence status.
http://www.ontarioimmigration.ca/en/pnp/OI_PNPSTUDENTS_JOB.html
Keep in mind there are on-going changes and future changes that are to come with the management and processing of immigration applications and there is no 100% way to predict or guarantee how any immigration application will unfold.
However, working with an experienced and savvy "think outside the box" immigration lawyer, before any application is submitted, who can prepare and present your application in the most favourable way (knowing how the immigration bureaucracy thinks and what factors will make an application look more promising) and navigate the web of immigration law and policy to avoid delays in processing or refusal, and manage your temporary status as a worker along the way, is key.
The answer to your question will depend on many factors that are not clear in your question: what is your nationality? do you hold an EU passport? What is your budget range? What is your risk profile like? Expected/desired ROI? What is your present age and retirement timeline? What is your preferred retirement weather (Helsinki and Dublin will, of course, be much different than Athens and Madrid)...
That said, there are too many "expert sources" predicting best bets but some good sources I've come across and based on my knowledge and travels through Europe are the following:
Good brief overview of hottest (Budapest, Hungary comes in as pick #1 for 2015)
More in depth analysis of European real estate market with Berlin coming in as pick #1 (see page 29, Chapter 3 "Markets to Watch"
http://www.pwc.com/en_IM/IM/publications/assets/emerging-trends-in-real-estate-europe--2015.pdf
Also citing Berlin as #1
http://ee24.com/articles/europe/the-best-cities-in-europe-for-real-estate-investments-2015/
Hope this helps a bit in making a decision.