I like the use of white space for #2. A little more strength would be good: thicker lines and space. I don't know if more angularity can be added without ruining the appeal. There is no space in 'migrate7'. And a minor emphasis on the 7 would help, maybe bump the font?
#53 is clean and interesting. But the symbol needs to usable alone which means the M and 7 need to be more identifiable. Possibilities: * use a color instead of the negative space * re-proportion the 7 to be more clearly a 7 * slant the symbol