Before I add my two cents to the discussion, I want to state that I personally concur with the position that the only “healthy” choice with regard to smoking is to avoid it altogether. Hence, my “analysis” below is nonsensical to begin with.
Having said that, an interesting consideration is the effect of cost and availability on the frequency and duration of smoking and, by extension, effects on health.
An individual cigarette costs much less than the typical cigar and cigarettes are packaged many to a pack. This may lead to increased smoking in the case of cigarettes, which would presumably increase the health risks of that product over cigars.
Also, cigars self-extinguish if not continuously puffed, whereas cigarettes continue burning and emitting fumes until they run out of leaves or are put out. So, theoretically, a casual cigar smoker could possibly have less exposure to fumes.
None of this does, however, provides any guidance as to whether the intensity, volume or composition of cigarette smoke is qualitatively better or worse than that of cigars. That would take a fairly rigorous study and is probably not all that meaningful in the long run.
Not smoking is the far cheaper, more convenient and healthier choice.