As one who has dabbled in both, smoking cigarettes will kill you. Smoking weed makes you hungry. Smoking anything is bad for you, but cigarettes are by far the worst.
I have also smoked both, and during the same time period, mainly during the 60’s and 70’s. I agree, smoking anything is not the best idea, but reefer smoke is much less harmful, especially when smoked through a bong with ice. Can also make awesome cookies, brownies, etc. It is also much easier to quit, or go without for an extended period of time. Plus the bennies...pot generally lifts your spirits, gives you an unending appetite (maybe not so much a bennie), is great for sleeping afterwards (indica), and the smoke does not seem to linger as long or smell as bad. Stale tobacco smoke is disgusting. I still appreciate a couple tokes now and then, gave up tobacco many years ago, and my oxygen level is 98%, and I’m well into my 70’s now.