I use my knife for everything and have been carrying one since I was six or so - about 44 years now. I used to carry those single blade like most of you posted. My wife got me a swiss army knife about 25 years ago and for me it simply works. Not as sexy as those single blades but way more functional. Anyway, here is what is currently in my pocket. 3 1/4" long.
I carry the 6" cold steel Ti-lite never let me down had the blade 3 years no sharpening stone's been near it still sharp enough to slice the **** out of your finger lol. def. a CRKT fan though just never bought one.
For about 3 years I carried a Kershaw Whirlwind but it was either lost or stolen. It was a great knife so I was not happy, but I replaced it with a Kershaw Blackout and I I like this knife even better than the Whirlwind. It has assisted opening and I have had it for about a year and it has never needed sharpening. I must say that assisted opening is quite possibly the best knife invention on the planet because it seems like every time I need my knife, I am holding something in one hand and only have one hand to open my knife.