There is some controversy about nuts. Besides some people being allergic to certain nuts, some people say nuts are hard to digest or nuts have phytic acid etc. etc. I feel that almost every society throughout generations has utilized nuts (in moderation of course). I believe nuts can be a very healthy part of one’s diet, as long as there are not allergies.
The Rambam, Maimonides, the greatest physician of all time said that almonds are the healthiest of all nuts. However, nowadays that may not be quite the same because of the way almonds are grown, processed etc. Also, some people cannot digest the skin of nuts and therefore it is better to soak and peel almonds.
Walnuts are a great source of omega 3 but should be used in moderation.
Too many nuts can cause nausea as they are rich and high in fats.
Pistachios are very healthy but again in moderation as they are very salty.
Peanuts are best avoided because they could contain certain molds that are not seen but are unhealthy. Nevertheless, once in a while it should be fine. (And in reality many people grew up on peanut butter sandwiches!)
Baked or roasted nuts are often not as healthy because heating the nuts may affect the healthy oils which could become a bit rancid. Also nuts must be stored in proper conditions so they last well. I prefer to store them in the freezer once opened.
I personally use nuts as a snack between meals and many cultures serve platters of fruits, dried fruits and nuts for dessert or snacks. It is far healthier than cookies and cakes or pretzels and chips.