I use a Big Green Egg - it was expensive, but it lasts virtually for ever and you can cook anything on it from dogs and burgers to Ribs and Pork butt to baked goods like pie, bread and pizza. I have cooked multiple pork butts on it for 30 hours straight without having to open the lid once or do anything to the coals.
cons:
price
the size of the grid might limit your quantities
price
I have the chargriller kamado akorn. It's the poor man's version of the big green egg that you can get at Lowes. It's certainly not the quality of the Egg, but its very versatile. You can smoke low and slow for long cooks or grill a burger or even a pizza at high temps.
The poster above that mentioned the importance of keeping a constant temperature for long periods is exactly right. I had cheap smokers before and was always frustrated with constantly having to monitor the temp and frequently adding charcoal and making adjustments. The kamado types of grills are very easy to use. Just set it and forget it. And they are incredibly efficient with charcoal. I never have to add more even during very long cooks.