What’s the deal with Russia? Pound-for-pound it’s the Poland, Ukraine, and Belarus that have suffered the most as far as countries are concerned from Nazi regime/occupation during ww2. Maybe
@stefan92 can elaborate, genuinely interested here.
I will try, but no guarantee for this to be all correct:
At first you are right when you talk about who suffered the most in WW2 due to German occupation, but even then it's mostly focused on the organised genocide on the jews, not on Poles, Belarussians etc as such. Russians also not. So because of Auschwitz, the Warsaw Ghetto etc Germany has a very special relationship to Israel, not really to Poland. Keep in mind, a lot of what today is Poland historically was the actual East Germany, and what today is called East Germany was Middle Germany - which still is present in things like the "Mitteldeutscher Rundfunk" being an East German regional TV station. So especially Poland is a territory were a lot of Germans actually have their ancestry and were forced to come as refugees into current Germany.
Russia was were it all went wrong in WW2. The trauma of losing a world war started with battles like Kursk or Stalingrad - all in Russia. Those countries you mentioned weren't such a big obstacle, especially not Poland, and therefore are not present as places were a terrible war happened - simply because it was over so fast. Russia is, and that's what the Germans don't want to repeat.
And it's not only about WW2 - at least since the 70s it was believed by many Germans that a strong German-Russian relationship would be key to tearing down the wall through Germany some day. Yes, I am aware that it was the Soviet Union at the time - but I do think we all agree the SU was dominated by Russians and used to oppress other peoples. So while not entirely correct to relate the SU just to the Russians I think it is ok when we are considering the power structure there. And it worked. Economic deals like the first gas pipelines worked for mutual benefit and in the end it paved the road to the peaceful reunion of Germany in 1990. The SU could have tried to bring the GDR back into the fold by force (like it sadly did try with your country) but it didn't. It's difficult to come to terms that a state is fighting cruel wars that here behaved reasonable and peaceful when it mattered most.
Looking further back into history (like to the time of Catherine the Great) you see a lot of German families who were invited to move to Russia - and lots of those moved back centuries later after the SU collapsed. A lot of those still are more or less fond of Russia and would like to see their two countries having close ties.
And finally a lot of Germans are quite critical of the US and see Russia as the natural counter weight. There is more or less of a solid base for them (considering the lies the US used to attack Iraq, their involvement in countless wars all over the world etc), but sadly some of those simply are stuck in a world view that sees Russia as the lesser evil (if evil at all) and necessary to balance the power in the world.
And I am sure there are a lot more facets to the topic of German-Russian relationship and mutual feelings that I didn't think about now.