The first and third one in your first picture are my favorites.
Some of them sort of remind me of the Timberline logo, but that's besides the point.
I really like the your work in regards to its emphasis on hard lines, geometry, and being devoid of color. Instead of just hard lines though maybe think of altering the density or using crosshatching to achieve the effect? In particular I'm thinking of: if you layered F and B they sort of match except for the lower R corner, maybe that is dense and where your lettering diverges you use cross hatching as opposed to black lines of varying thickness. That's confusing. Haha, I hope you get what I'm saying.
When I've done this in the past it's always helped to begin with a basic concept and explode it into a bunch of confusing and more complex iterations, figure out the elements I like best and re-begin the process. Looks like that's what you're doing, thumbs up. Just don't get stuck in the repeating the same elements again and again, take a walk and come back to it with some fresh eyes. Keep going!
