Germany is greater than Poland, Czechia, Slovakia, and Lithuania combined, as of now.

                                                            I will merely be listing bullet points, I hope to go more in depth in the future rounds.
Economy
Economically Germany is much better off. Germany’s GDP is 3.997 trillion dollars, but the combined wealth of the 4 other nations combined is merely 995.732 billion dollars. A difference of 401%.
Germany exports 1.401 trillion dollars annually, but the 4 other nations combined merely export 485.75 billion dollars worth of goods annually.
Freedom
Germany is freer than all 4 of these nations for freedom, ranking 13th world wide. Once again Germany trounces the 4 other countries for democracy as well.

Education
Education is also on Germany’s side, with them being 5th place world wide, higher than any of the other 4 nations.

Demographics
Germany has a population much larger than the 4 nations combined. Germany’s population is 83,042,200, but the other 4 nations have a population of 57,298,380‬.
                   
Life Expectancy
Germany has a higher life expectancy than any of the other 4 nations.
                   
Quality of Life
Germany has a superior quality of life to all 4 of those nations, with Germany ranking 8th as of 2019.
Germany is also a superior nation to be born in.
                   
Tourism
Germany makes is a more popular tourist destination than all 4 other nations combined.

I guess I'll waive so my opponent can make his case.

Germany is #1.