I carry an Opinel everyday. They are great for the following reasons:

- Traditional french knife with a rich history

- Cheap (from $ 8)

- Mechanically very simple

- Lockable

- Many sizes available

- Stainless steel and carbon steel available (I prefer carbon because I like the patina)

- They can't be opened with one hand which would make it illegal to carry them publicly in Germany

The biggest disadvantage is the untreated wood handle. It can swell up if it gets wet which makes the knife harder to open and close. Some people deep fry the knife to make the wood water resistant.