In terms of current men's suit styles, there seems to be only two selections: two- or three-button (double-breasted is not as commonly available as these two).
Three-buttons come up high, so the lapel ends pretty fast. This emphasizes the chest and belly while under-focusing the shoulders, meaning that unless one is in great shape, one can easily look like a stuffed cabbage.
Most of the tie is tucked away; ties, pinstripes, vertical stripes in general tend to have a slimming affect. If the length of the tie can't be seen, bummer for false svelteness.
|I'm sorry, it's just not going to work out.|
The two-button, however, has a wider and longer lapel, giving the shoulders an appearance of broadness. Broad shoulders mean thinner waist by comparison. More of the tie can be seen, giving a longer line. And since less of the torso is buttoned up, less like a stuffed shirt will one look.