Well I only chain smoke if I'm really stressed out but I do smoke more than is healthy.
Not very brand loyal, right now I've got a pack of Pall Mall Menthols. Previous pack was some Luckies. Before that maybe Camels, not sure.
Really I like to roll my own though, just the act of rolling gives me pleasure. When I can be bothered to go all the way to a tobacconist I buy Manitou (yellow pack), a German additive-free RYO tobacco. They also have an organic version (green pack), like actually organically grown tobacco instead of just "not full of extra chemicals", but it tastes like crap. :D When I can't be bothered I'll use whatever RYO tobacco depending on what's available, menthol usually.
Started with Marlboro Reds as a kid (11yo) and smoked them during my teens. Don't really find them very special in any kind of way anymore but not bad either.
AnythingEverything: 3 packs a day? Are you ever awake without a lit cigarette in your mouth? :D