My options are Italy, czech republic, Croatia, hungary, or Denmark.
I know nothing about europe so I dont know what my final destination should be. This will likely be a short visit (1 week or so) so I likely wont be able to tour the entire country that I choose. With that being said, its best to go to a place that has one or two really cool attractions or towns or cities to visit!
If its of any reference, I am already going to be visiting England, netherlands, Belgium, Germany, Austria, and Switzerland. I would like my last destination country have something that is unique apart from these countries that I am already visiting (ie. I will be seeing mountains in Switzerland and Austria, so I dont need my last destination to be oriented around seeing yet more mountain landscapes.

Italy man !!! so many amazing places to see there !
I’d go to Italy
Italy or Hungary they’re beautiful but just do research on them
at the moment i’m dying to go to denmark so i’d say that. if you choose italy, stay in the north; the south isn’t so nice
I would say Italy. There’s Rome, Naples, Florence, Venice (definitely worth a visit), the area around Lake Como is nice, and I have heard that Tuscany is incredibly beautiful.
You should visit Croatia Dubrovnik or one of the islands (Hvar, Brac) it’s really something u don’ want to miss.
To help you make decision check: http://www.connectotravel.com/ there you can find photos of places you can visit in Croatia and various types of accommodation there.
Hungary. Buda Pest is really great in the night and after you visit the city you know why I wrote Buda Pest