I don't know about the Portland area, but in southern Oregon I am raising a bumper crop of poison oak this year. We also have wild blackberrys in abundance. The thorns aren't as long as prickly pear, but they are a lot faster-growing, and being on vines makes them more mobile.
I have limited experience with prickley pear, but would much rather deal with it than poison oak. Just wait 'til you have to go out in the woods, and you will discover what body part it transfers to from your hands.