I'm not saying that the best thing about Vienna is the highway that get away from it (LOL), but as a foreigner it's the perfect "beach head" to explore the continent (and Eastern EU is crazy fun, people are more can-do than can't-do. There are a billion other reasons such as history, culture, cuisine, outdoor & sports ... Taxes are high (like everywhere in EU) but you get decent healthcare. Also salaries in IT are good especially if you are freelancing pretty identical to Germany. (avg > €60,-/hrs).
Another one of my fav is Berlin. Salaries not as high but fantastic software / start-up ecosystem. City is very affordable compared to other parts of Europe so lower salary is not huge issue.
disclosure: I'm Austrian (though have lived outside Austria the past 20+ years)
EDIT: typos