Why so many cigar shapes and sizes? The size and shape of cigar dictates how long the cigar will burn, influences the flavor, and differentiates the overall experience.
The 3 big influencers:
1) Ring gauge: bigger ring gauges can pack more of a "punch" of flavor. The bigger the ring gauge, the more tobacco that is lit up with each puff.
2) Overall size/length of cigar: the bigger or longer the cigar the longer it normally takes one to smoke it.
3) Shape: this all comes down to preference. Some people like the way a smaller cigar sits in their hand. Some like the way a torpedo is tapered at the foot and the way it sits on the lips when you smoke it.