Here is a link to a guy's site that tests charcoal.
http://www.nakedwhiz.com/lump.htm
Note he primarily focuses on the types of lump charcoal out there, and does not care for briquettes (AKA kingsford).
After getting into low & slow BBQ for a while, I primarily use lump charcoal. This is for a couple reasons--Lump burns hotter (but quicker) than the briquettes, but produces little to no ash. If I am smoking something for more than 4 hours using Kingsford, the ash produced will clog the air intakes on my smoker. Kingsford briquettes produce 3-4 times the volume of ash that the same quantity of lump will produce..
For DO cooking, the standard briquettes work well, and it is easier to tell how much you are using by just counting the # used as they are uniform in size, and ash production is a non-issue, generally.
Personally, I like both Royal Oak and Cowboy brand lump charcoal for grilling and smoking, as there are no fillers and coal in them, which I don't want in my food. Generally I just use kingsford (its easier to find) for DO cooking.
And yes, I swear by my chimney starter. If you don't have one, get one--you will never go back. They light coals REALLY quick if you put them over the propane flame on a outdoor turkey cooker. (ready to cook in 10-12 minutes, vs. 20-30)