No actual experience entering any of the three...on my last trip south there was a deep low outside that kept me inside..I didn't get out until the Cape Fear.
There's a large fishing fleet that uses Oregon. (They Buzzed by me at 5 am.)...from what local info I could gather, they are all tricky, in anything but good weather. Good Local knowledge would be advisable. Perhaps even following someone in. Once inside Oregon, the flats are pretty shoal, watch the current and your depth.
Hopefully you'll get more first hand info.. on here..