Hey, @piotrgrafik.

For what my opinion is ultimately worth, I think your instincts to go with a circular kind of logo are sound, and so is the concept of less is more. To that end, I think the second logo from the left of the RGB group is the best. It is the least busy, the colors show up well and you definitely get as strong letter M.

Plus, it reminds me in design of the helmet the Marvel villain Magneto wears. :)

Maybe that's not necessarily a plus, but I still think it's cool. :)