Which of the following countries claims to have "the most modern resort in eastern europe " answer poland hungary bulgaria romaniabulgaria claims to have "the most modern resort in eastern europe "?

For beach resorts, that would be Turkey. In the last few years, they put huge investments in their tourism industry and a lot of efforts in modernizing their resorts. Perhaps the most popular and eventually the best Turkey resort is Antalya. It is a very modern tourist destination, compatible with any Western Europe resorts in terms of attractions, service and prices. Plus, it is spiced up a little with the taste of the Orient. The diversity of products is wide and you can find what you are looking for whether you look for a family vacation or for wild night life. 

If you look for something more "inside Europe", Greece and Croatia are the only Eastern countries that can offer high quality tourism products. 

For winter sports probably the best resort would be "Bansko" in Bulgaria. It is still in process of development though.