I think it really depends on your choice of airline.

If you are flying UA, then the RCC is clearly your best choice as you will want club access in the UA terminals at SFO, LAX & DEN (plus access to HP clubs at PHX and LAS).

If you are flying HP or a combination of UA/HP, RCC is still your best choice for the same reason.

If you are flying DL (don't know if PDX is still a DL hub or "focus city") then you may find PP to be more useful though I'd bet the DL club at PDX is excluded.

In general Priority Pass is better for international travel as it doesn't usually include access to hub city clubs (i.e. no UA at ORD, no AA at DFW, etc.) Also, one of the main benefits of RCC membership - as noted above and referenced in many FT posts - is access to the RCC staff for handing missed/cancelled/changed/delayed/upgraded itineraries. You generally won't find that kind of assistance at a priority pass club unless it happens to be affiliated with the airline you are flying that day.