My main features are a pocket clip, thumb assist, blade lock, and blade hardness (not to mention how it fits in yer hand). I have a number of blades with different blade lengths and edges, but the one I keep in my pocket for daily use is the Browning Mountain TI
3". The handle is just right for my hand and it's not too intrusive a size so as to be bulky or obvious. At around $20 you can't go wrong. When needed, I've pulled it completely apart with an allen wrench set, cleaned it, and put it back together in just a few minutes. It always holds its edge.