Marc Broussard

According to this archived data from a live recording of a Marc Broussard concert, the audio source is a Neumann KM184, elevated 9 feet high (presumably 9 feet off the ground, over the band).

In the attached video, Marc is using a Shure SM58 throughout (most visibly around 1:29).

In the attached video, Marc is using a Sennheiser microphone, and based on its specifications, it appears to be the MD 441U.

In the attached performance, Marc is singing into an RE20 throughout.

In a promotional image for Marc Broussard's tours, he is shown singing into a Shure KSM8 Dualdyne microphone, indicating its use during his performances.

In this video, Marc is singing into an RCA 44 style microphone. Based on its condition and application, I assume it's not a replica like AEA has released in recent years, and based on the stripes on the lower part of the microphone's casing, I believe this is an RCA 44-BX.

In this video, a cover of "Bring It On Home To Me" by Sam Cooke, Marc Broussard is singing into a Neumann M 49 microphone, starting around 27 seconds into the performance.

In this video, a live version of his song "Honesty", Marc Broussard is singing into an SM7 style microphone starting around 16 seconds into the video. I'm assuming it's an SM7b because of the top of the microphone's grill (or front of the mic), but because of the video quality, and the fact that the build of the vintage SM7 and the updated SM7b are so similar otherwise, it's difficult to be certain on this video alone unless further information is presented. Odds are high he's used both at some point over the course of his career, though.