MariS, welcome to SMF! Be sure to stop in over at the Roll Call section so folks can say "hi."
Wow, lump or briquettes? You trying to start WWIII? in some circles, dem's figh'n words. Not here though. It is a valid question for those with a new smoker.
Each type has its loyal followers. Lump is a "pure" charcoal, just carbonized wood. Due to the fact it is tree branches and varies greatly in size, there is a LOT more surface area in contact with air when it burns. Consequently, it burns hotter and faster than briquettes. I use lump for hot n fast smokes, like poultry. Others use lump for everything, with Royal Oak being readily available to most. The worst brands use furniture and lumber scraps. The best brands just use only hardwood trees. Lump is pricier than briquettes, usually in the 60 cents to $1 per pound range.
Briquettes have their advantages and disadvantages too. That's where brand names enter the picture and people become fiercely loyal to their brand. The worst brands contain wood char, chemicals, neutral and natural binders (like sawdust, limestone, and water). The best brands leave the chemicals out. Kingsford Original, also known as Kingsford Blue Bag, aka KBB, does use chemicals, but it is cheap and well marketed. Unfortunately they've changed the formula many times in the last ten years. The current formula burns up quickly because it is made for the grill, not the smoker.
Royal Oak makes briquettes called Ridge, but they also use the same briquette packaged with store brand names, especially grocery stores. At Lowes, you can find Royal Oak Ridge. At Home Depot, the same briquette is called Embers. Winco, Kroger, and many others use Ridge briquettes for their brand. Look on the back of the bag at your grocery store. If it says "Made by Royal Oak Enterprises," it is a Ridge briquette.
Ridge leaves the chemicals out and is a dense briquette. It burns longer and maintains temps better due to uniform size. I've run Ridge from 145F to 450F in my smoker and it performs like a champ. It is typically in the 26 cents to 39 cents per pound range.
Trader Joes and Weber make great briquettes too, but they're pricy because they contain up to 95% wood char. They run about the same price as lump.
Finding what you like best for performance and taste is a lot of the fun of smoking meat. Bottom line, it is just a heat source. Buy several different brands and types to see what you prefer.
Now's a good time to watch for clearance sales at the big box stores and grocery stores. Plenty of good deals out there on charcoal.
Have fun!
Ray