Depends on the hand.
I don't like tiny knives for extended uses. When I pull out a little knife to trim something, it's just fine, but when I'm going to be working with a knife for a while, I prefer to have a larger handle. Because of that, I don't own an SAK classic or a peanut (that tiny Imperial jacknife hiding in my safe doesn't count!! It's just like my first knife, that's the only reason I have it, and I don't carry it!! Doesn't count, it's not a peanut!! Not ever been sharpened, anyway) since when I go to use one of those, I have to kind of laugh. Doesn't work for me. Others like them, and that's fine. In fact, my wife's Classic is the first knife she's actually liked enough to always carry and never lose.
3" long is as short as I'll go, and I usually go with something 3.5" to 4" long. Fits better, and if it has two blades (one short and one long), that's enough for me most of the time. I'm partial to Case Copperheads overall, but not adverse to carrying other stuff.