I like how #15 distinguishes the 2 entities that the bridge is bringing together through the color contrast. I also like how the bridge resembles people and CTCF acts as the pillars of the bridge. What would make it even better? Perhaps further develop the concept of the 2 entities that are being brought together?
Once you you have understood the idea, the logo works. That delights me. Stable foundation (CTCF), the basis for communication between different organizations through Bridge by people.