Here are some blogs that I recommend:
Pedestrian Observations: This blog is written by Alon Levy, a mathematician who writes about transit. This blog primarily focuses on rail transit, although buses are discussed. Alon has lived in multiple countries and brings a focus on identifying international best practices. Most developed countries have better transit than the United States, so this international perspective is invaluable.
Human Transit: This blog is written by Jarrett Walker, who is a transit consultant who specializes in bus systems. He has been involved in bus system redesigns in several cities around the world.
Kostelec Planning: This blog is written by Don Kostelec. Don is a transportation planner who has written extensively about how to make streets safer for vulnerable street users such as pedestrians and cyclists.