I always use charcoal briquettes because of their even shape and size. I also found they have a more constant quality when compared with regular lump charcoal (mostly "small" lump charcoal, that is...).
I found out the hard way (yes yes, sometimes things go wrong here as well...) that with charcoal briquettes it is easier to control and maintain the fire and barbecue temperature than when using the regular "lump" charcoal.
Briquettes have a More Even Shape and Size
I feel that the improved control over the fire and heat inside the barbeque is probably due to the round shape and even size of the charcoal briquettes and the resulting more even pattern and size of void space in between the coals. (i.e. the porosity of the burning coal mass)
With a more even size of void space in between the charcoal briquets, the flow of oxygen in between the coals can be governed easier. Thereby you gain better control over the burn speed of the coalfire, and over the temperature inside the barbecue.
Once coal and fire have become a (more or less) constant factor, it is easier to repeat previous good experiences, or to properly adjust a recipe or smoking time to improve on previous experiences.
If you have any suggestions comments or queries about bbq, charcoal or briquets: