Is the USA still the best country to come to as an Immigrant and have great opportunities for a better life?

Its still a great place, for anyone who wants to legally immigrate. I think some of the feedback you are hearing comes from the fact that the US has always been viewed globally as a land of opportunity, without it being understood that just like any other country, we have our own set of issues and problems. When people get here and realize its not perfect, they are dissatisfied. But, compared to many countries in the world, yes, the U.S. has a LOT to offer, just understand that it is not a Utopia with streets paved of gold. It is a good place to live, and there are chances to go far if a person is willing to work hard and apply themselves.