Europe is a big place, where you go will be influenced by your own interests. The question you have asked is a little like asking "where should I go in the world?" Europe is a lot more geographically diverse than the US - a lot more history has let small countries develop quirks which separate them from their neighbours, much more so than between the US states. Perhaps a little more information about what you hope to do and like doing would help us? Also, telling us where you are from will give an indication of what temps you are used to, so what you would consider cold.
You could also try searching this forum with a search word such as Europe or the cities you suggest in the thread title... you'll be able to see what advice has been given previously.