I am not an expert but since no one else responded, I'd say since the coupons are cut off, the grading doesn't really matter too much. if they both have a similar eye appeal, they are both probably worth around the same.
Edit: I removed my valuation... Rhett is correct, 1920 Z's are worth more then most. I'm relatively new to collecting the set... It's actually really fun to collect 'em. I highly recommend it
