Hypothetical Alien Situation

I was thinking about what it would be like to invite an alien species to live on earth as our equals. I was thinking that it would only work if they were really similar to us in intelligence, or at least the same range of intelligence and ability as humans.

If they were less intelligent, people would look at them as a burden on society. They might end up as criminals, drug addicts, etc. If they were more intelligent, people would view them as too much of a competitive threat and that humans would end up being subservient to them.

I wonder which situation would be MORE threatening to humans.

Any thoughts?