Lefty: Buy the biggest one that will fit in your fire box. Better yet, buy some expanded metal from Home Depot and make your own. Do a google search for building ideas. You don't need access to welding equipment - I bolted mine together. I used angle iron to make the frame and bolted the expanded metal to it. Total cost was about $30. The charcoal basket will help with your temperature control.
I don't know which fuel your using but my preference is lump charcoal -- it burns hotter than briquette and leaves little ash. I start my Lang with a weed burner and a bed of lump and some cheap camp fire wood, which burns hot and fast. The chimney is open as are the pin wheels. Once I get a bed of coals and clear smoke coming out of the chimney I add the meat and chunk from Home depot -- hardwood is hard to come by in Tucson and expensive. Once the internal temperature of the meat hits about 145F it won't take anymore smoke so I finish with lump.
These smokers aren't like cooking with propane -- you can't set it and forget it. You have to watch your cookers temp and when the temp starts to dip you have to add more fuel -- that's why the lounge chair and beer was invented!! I control my temp with the pinwheels. These smokers take some time to master.