I would do this to alternative 6

I like alternative 5 very much, is really clean.

I also like very much the rectangular keys on the left and right panels, on both alternatives.

The solid border lines eliminate completely the hint of negative spaces left on alternative 2.

I have a little bit of a problem with alternative 6 at the corners of the character and the punctuation/numbers areas where there is a solid black pixel that seems to stand out a little. Alternative 7 eliminates these black corner pixels.

I still think I like alternative 5 the best.

Erwin