I am pretty sure rabbi's have been attacked in other countries too
Feel most welcome to name other European nations where the Chief Rabbi of the country was attacked in the street. Or just continue with the off-topic and ad hom posts. I wonder which you'll choose.
So why is it so freaking difficult to admit Poland was the most welcoming place for them?
If the UK passed a new law forbidding Poles from living in London and most of the bigger cities, would you then say that the UK was a welcoming place for Poles?
Pre-partitions Poland had laws forbidding Jews from living in Warsaw and most of the bigger cities, so why do you claim that Poland was the most welcoming place for Jews then?
Poland was not a welcoming place for Jews, but it was less unwelcoming than other countries in Europe.
So why did they keep on settling here?
Because, as has already been pointed out to you, Poland was less hostile, and more pragmatic, than other European countries.