What are the benefits of eating; walnuts, almonds, pecans etc.?

I love pecans, almonds, walnuts, pistachios. I don't care much for nuts like cashews or peanuts.

I wanted to know how nuts such as those listed help your body and how you should eat them on a daily basis to better your chances of healthy eating.

Are any nuts better to eat than the other?

Is there a best 'nut' to eat as far as health is concerned?

Thank you