Are people nicer who don't have religion in their lives
No, I don't find a correlation between goodness and religion either way, I think it's more like Stevie Wonder said,
'there's good and bad in everyone'.
I do think that non religious people have their eyes open more though, which I guess is a personal bias based on my non belief.
People are people. We all have our priorities and our pain points and a lot of the mean is people reacting to pain in other parts of their lives. Religion just gives us one more reason to be different.