Do you want wood fired, electric, gas? Do you want it to be mobile? About the only thing you'll see in this part of the country is wood fired. And I think most will agree, the best Q-joints use wood fired pits.
There is one Q-joint in Springfield (Missouri) that uses nothing but Brinkman offsets. They have about 10 of them going at any one time. And they have been around forever. Probably the best and busiest Q in Springfield. I suspect they use the small smokers so they can adjust by the amount of business they expect, rather than having a huge pit going all the time.
But there are others here that have the huge ones. Most of them look to be custom or owner built.