Far and away ... Pistachios ... followed by a tie with Almonds and Cashews ... even if they're fruits I guess.
Peanuts to round everything out, but won't turn down others.
I grew up with nuts in baked goods and it makes me sad that so many young people don’t seem to care for them.
I think that it’s purely economics when moms stopped adding walnuts to brownies, chocolate chip cookies, etc…
If you get the chance, gather some wild butternuts in the fall and give them a try, they are a lot of work but something that IMO is well worth the effort , the same with wild black walnuts.