Assuming we're talking about folders - pretty much any good brand will do the job(Benchmade, SOG, Spyderco, etc.)
I personally carry SOG Flash II - very nice EDC knife IMO.
3.5 blade is a limit (from what I understand)
Autos are no go, unless you're LEO (again from my understanding)
I've tried EDC fixed blade - not my thing/too much attention..