They are actually a little different. The Tsardom of Russia lasted from 1547-1729, while the Russian Empire was from 1729-1917. Peter the Great turned Russia into an empire from just a kingdom (Tsardom)
As for me, I prefer the Russian Empire. It lasted much longer than the USSR, and had a lot more land territory. I'm also a Monarchist, so I would support the Monarchy over Communism.
For me though, the Soviet Union was the worst of those 4. I'm anti-Communist, and some of my grandparents and great-grandparents suffered from the hands of Communism.
For you, Stalin will rise, but for me, Peter the Great will rise!