NOOOOOO ... don't use the logo as a letter, that's corny, unless you want to use MS Comic Sans as a font.
I like the 2nd cover best, it's very, very appealing. Maybe reduce the size of the icon in the other two covers to match the second one
Also, the third cover is a lot nicer to look at than the first, if you#re uncertain, try using the setup from the third for the first (Name - title - Logo)
The blue icon on a blueish background is hard to see, I'd make it white with some transparency.