Four corners? I actually see four squares and sixteen corners. :-)

8 or 10. But try centering the "o" vertically because it looks odd to me. I bet this might look good with 90degree cornered boxes instead of rounded corners.

You could also try adding a slug line to explain the company's function.

The business cards definitely aren't working. this logo is strong enough to stand on its own without text sharing or overlapping the green space.

I like number 10. Great logo!

6 for me - all the rest has been said!

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