I usually carry 2 knives - a SAK and a modern folder. SAK hasn't changed in a long while (Vic Super Tinker). The modern folder is just whatever I grab in the morning. Normally, that's a random selection from: Leek, Skyline, Delica, Mini-Grip. Recently (past few weeks), I've been carrying my 0550 while deciding if it makes it into the regular rotation or not.
As I get new knives, I try them out to see if they make it into the main rotation (currently the Leek, Skyline, Delica, Mini-Grip). If it makes the cut (no pun intended), it joins the others (sometimes replacing instead of joining) for random selection for EDC. I do occasionally revisit the others in my collection, so they do still see some pocket time. So far, though, none have made it back to the starting lineup.