Here is the first published BBH from O3: GW190412.
GW190412 is the first BBH merger for which we can undoubtedly say that the masses of the two black holes are not equal. Dynamicists know that this strongly favours a dynamical formation for GW190412. For example, take a look at Figure 8 of our recent paper Di Carlo et al. 2019
Have a nice weekend and enjoy the new LVC paper