Mine are:
Iran
Jordan
Syria
Lebanon
Egypt
Ukraine
Seeing how many people have Russia on their lists, I feel very fortunate to have spent a reasonable amount of time there, and been to Moscow, St Petersburg and various other places. I spent several months living a studying there as part of my degree in the 1990s, and visited for holidays in the late 90s and 2000s.
I've travelled on various sleeper trains in Russia, including across Siberia. We stopped off at 4 different cities on the way to Vladivostok, so had breaks from the train. I did really enjoy the train — we spent out time talking, reading, sleeping, watching the world go by outside the window, having train picnics, chatting to Russian passengers and sharing food with them. The landscape seen from the train isn't stunningly beautiful, but I still loved seeing the forests, the fields, the small villages in the middle of nowhere, the large cities we passed through, the rice fields in the far East. We were mostly in 3rd class, which is open plan bunks, so had a very Russian experience. I'd probably go 2nd class if I went again now I'm 30 years older. I fell in love with Russia and its people, and once it has a different leader and it's safe to do so I'll be going back.