Technically per IRC prescription you'd need R7.5 on the exterior of the sheathing with 2x6 construction in zone 5, but only R3.75 in zone 4, so you're probably going to be fine if you used XPS or iso. With 1" polyiso you'd be at R5.5 on the coldest day of the year, but closer to R6 most of the time, and the foil facer would better resist high moisture drives from sun-on-rain/dew wetted masonry.
A flash-foam inch of closed cell is still barely a minimum class-II vapor retarder at worst, and usually in class-III territory. Similarly an inch of XPS is also usually in class-III vapor retarder, and 1" of unfaced EPS is WAY into class-III, so don't sweat it if you go that route- it can dry in either direction. XPS would be a better than EPS for protecting against exterior drives, and you'd have ~1.2 perms of drying capacity in each direction. But with a cellulose cavity fill for moisture buffering 1" XPS and NO closed cell spray would likely keep the peak moisture down, and have 4x the drying rate toward the interior.
With foil-faced iso it's a true class-I vapor retarder/barrier which protects better against the masonry, but the R-value becomes more critical. If you go that route it's best if you use cellulose (or cotton batts, if batts are your only option), which would be protective of the wood due to the moisture buffering capacity of the fiber. While it limits it to drying toward the interior it's a good way to go, skipping the spray foam.
And keep in mind, air-tightness of both the CDX and gypsum would trump any of the vapor permeance issues. Caulk every stud & plate to the sheathing, and the bottom plate to the subfloor as your primary air barrier, and it'll be just fine.
If you use fiberglass or rock wool batts it's better to go with high-density goods like R21-HD "cathedral ceiling" fiberglass or R22 Roxul, since they are an order of magnitude more air-retardent than cheap R19s and low density R22s. With R6 on the exterior you'd still be in pretty good shape with R22 cavity fill in that climate.
Note, low density R22 fiiberglass only performs at R19 when compressed to 5.5" in a 2x6 cavity, whereas HD R21s perform at R21, go figure!? Similarly, R19s only perform at R18 installed per the manufacturers' instructions the cavity they were designed for- that's sleazy marketing for you! R22 rock wool is a true R22, not fluff-factor R22 like some fiberglass products. (Lowes carries Roxul products these days, if you can't find it elsewhere. Even though rock wools somewhat itchier than fiberglass I find it easier to trim & install, and doesn't leave as big a cloud of fiber in the air to breathe in.)
From a raw thermal performance point of view:
With R6 iso and R22 batts you'd be just shy of R20 whole-wall at a 25% framing fraction (typical, for 16" o.c. framing.)
If cellulose instead of Roxul it would be about R19.
Subract 1 from either if the above if using 1" XPS instead of iso, subtract 2 if EPS.
With flash'n'batt, no exterior foam you'd be a hair under R15.