I always carry a knife of some kind. My good knife is a Chris Reeve Mnandi
(link). I like a knife that I can clip to my front pocket (all my knives clip). The Mnandi clip is designed to look like a pen once it is clipped on your pocket. In my pocket, it looks just like a pen...very few folks can tell it's a knife. The knife is really nice...wicked sharp and very smooth. It is almost too nice to use on tape and cardboard! It's great for peeling an apple though...This one was a gift from my wife...they are kind of pricey. It's the only Chris Reeve knife I own, but it is really a sweet knife and I would buy another one without hesitation.
My other knives are Benchmades...also great knives.
My "everyday" knife is a Benchmade Switchback
(link) that I fell in love with at the Outlaw Cigar Shop in KC but bought locally (mostly due to the hassle of getting it home on the plane). It's also very nice. I like the long straight blade for "office" work.
My weekend knife is also a Benchmade, the AFCK. I have the old model (liner lock), the new ones are all axis lock models. Here's a
(link). Several blades are offered and I have the partially serated one...I've had the knife for over 10 years and it's showing some age.
The axis lock is a very strong lock and seems to wear better. My son uses a Benchmade axis lock that is close to 5 years old and the lock is still solid. My liner lock Benchmade occasionally suffers a lock failure. To be fair to the knife, I've semi-abused it over the years by dropping it, prying with it and cutting all kinds of stuff inappropriate for a pocket knife.
My daughter carried a CRKT knife for years until she lost it. It was also a good knife.
edits:typos