Both have equally bad effects on health. Individually, cannabis and tobacco produce the same constituents and quantities of chemicals known to be toxic to respiratory tissue, other than nicotine. Just three marijuana joints a day causes the same damage to the lung’s airways as 20 cigarettes, mainly because of the way joints are smoked. Tar from cannabis cigarettes contains up to 50 per cent higher concentrations of carcinogens benzathracenes and benzpyrenes than tobacco smoke. But even tobacco has these cancer causing agents.
I believe there is no comparison between two bad things. And as an educated person we should not get into any activity which is harmful for health. 🙂