For larger smokes (including the brisket I posted), I'm using an older model Charbroil offset smoker, similar to this,
but the older model is a lot more heavy duty... much thicker steel on the walls and doors. And the chimney is attached on the side, at the level of the cooking surface.
I added stove "rope gasket" seals around the doors, and added a baffle plate inside the main cook chamber to try to even out the temps side to side.
I've also got a cheap vertical charcoal smoker that I use for smaller items and usually shorter smokes:
It was a cheap one from walmart. Did some mods to it as well (rope gasket seals and an improved charcoal pan, and it performs great. Small cooking grate size and small charcoal pan size are the only reasons I don't use it more. It uses a lot less fuel and heats up quicker than the offset smoker, so it still gets some use.