Just found thread, and as people said before, unreal brush editor sucks, and while I used hammer, it took way more time to do an level compared to make it from a 3D program.
Also, another problem is dealing with detailed enviroment, to make detailed walls and etc would take way much more time in brush editors than in an 3D program, that’s why I think gave up on them and decided to use only for prototyping levels.
Not sure about the Radiant from BO3, but if solves these problems, then it will be a nice for unreal, one of the advantages in the brush editors were the pre made UVs, so you could already apply the texture on it.