I like #23 and 23, but I am afraid they would look like a stripe on a business card and get overwhelmed by the other info on the card. What do you think about making the letters taller?
#18 is still my favorite. But I would like to see that is some other color combinations. Also can you try making the "solutions...." a it larger and/or darker so it is easier to see.
Also, would like to see #22 and 23 with taller letters.