-The ones with 4-5 lines of text feel like too much to read for just a postcard.
-The shortened versions of the quotes on the mobile layouts are better.
-Try darkening some of the background images so the text shows up better- it's pretty hard to read in about half of them.
-Maybe positioning the text in areas of the photos where there's a lot of dark space would help?
-Most of all just make sure the white text isn't disrupted by business in the background & isn't on top of anything light in the photos.
-If there isn't a dark spot in the photo to move the text to maybe try a drop shadow.