Fidget toys are very personal gadgets, and there is no perfect fit for everyone. I've got a post where I explain why they aren't just for those with ADHD and how they can help survivors of an abusive relationship.
This beauty is one of my favourites. It was small enough to fit in my pocket, it doesn't make any noise, it had a great weight to it, and I could hold it in my hand under the desk during meetings without anyone being aware. It keeps me present, focused, and the repetitive action is very calming to me.