I bought an Opinel Carbon just last week. I got the size 9. It lives in my work laptop bag and comes with me every day. I also got the Opinel non-Carbon (stainless?) size 7 for my wife, and she has been using it a lot to open packages, food cartons, etc. Its handy just to have a sharp knife at hand when you need it. The Opinel models are very good for the price.

The Leatherman isn’t under 100 bucks, at least not in the Netherlands. My Wave + was 150 bucks. Still massively worth it, though.