I'm a big fan of the Dozier Modified Personal - just a smidge under 7 inches, overall...but, again, it really depends on what you're going to be doing with it. D2 is great for general cutting/slicing; but if you're going to start hacking at things, it isn't the best choice (not that there's much hacking to be done with a 3 inch blade, but people never cease to surprise me).
I really like my Enzo Trapper in 01 steel - overall length, off the top of my head, about 8 inches (3.75 inch blade). The scandi grind is about the easiest to maintain.
Bark River, as mentioned, has some very nice options.
I agree with the recommendation on the BK16. I found the BK11 didn't fit my hand well, but the grinding stone on my Dremel fixed that.
Gray Wolf Knives makes some nice, affordable knives.
There are bunches going through the Knife Makers section of the classifieds on this site; and you can get some great deals there (as well as the Individual Sales section)
To be honest, passing the 4" blade mark on an EDC fixed blade can create some unnecessary hassles. People notice. Make sure you know your local laws before you start carrying...and, if questioned, never say you are carrying it for self defense. It's a tool - don't put it into the Weapon category.
Edited to add:
This might help put things into perspective a little more
From left to right: BK15, BK16, DPx HEFT4, ESEE4, Gray Wolves Knifes M7, Kellam Wolverine, Enzo Trapper, Bark River Gunny, BK11, Dozier Personal