Maybe too soon to say. . .
I quit both at the same time. With rare exceptions (like beach trips with smoking girlfriends) I only smoked when I drank. Which of course meant every day, but only in the afternoons and evenings (small favors, I never was a morning or midday drinker). Some days that meant half a pack or more, depending.
Today is day 19 for me, it's been pretty bad in terms of mood swings and depression. At this point I can't separate the booze and the smokes in terms of what's driving my mood but I guess I thought about it like a band aid - rip it off all at once and get it over with. Since alcohol and cigarettes were so entwined for me I also thought if I continued smoking without drinking I might just ingrain the smoking habit even more deeply.