Logo Design Exploration

Here's what I'm currently working on. These are the initial icon concepts for an educational thing (can't tell you what it's for just yet).

I'd love to hear feedback on which ones you feel are most visually pleasing as well as if there's anything I can do to improve upon any of these marks (@Jeroen van Eerden I would love to hear your thoughts). The only comment I can make in regards to the client is they want the final concept to be put in a "badge style" layout.

Thanks for the feedback!