#19 is my favorite. I like the lower case "it". Could you break up the second line in the F so that it is the dot for the I where it is like a hyphen? It makes the F stronger. Does that make sense?
I like the orange, but could you also do the same thing in navy blue and silver? try a couple different color schemes? Maybe yellow?
#31 and #32 look great. But can you make the F stand out more? It is too plain. Maybe a different font. I like bold strong fonts so something that is not boring but strong. Actually, can you try different fonts for the "F it"?