Joe is correct - all other things being equal, a longer stroke gives improved low speed scavenging and better low speed torque, but has weaker high speed performance due to higher frictional losses and limitations on maximum valve size caused by the small bore. However large bores cause combustion chambers to have large surface areas, increasing noxious exhaust emissions - and this means additional control measures have to be taken, which may reduce power and fuel economy. The outcome of all this is that modern engines broadly aim for a stroke of 1.1 times the bore, as the best overall compromise.
Some of the small Briggs engines have bores bigger than the stroke ("oversquare") which was an idea that seemed good at the time (mainly in the 1960s and early 1970s) but turned out not to be good in practice. However remember that what Briggs did was to make a range of engine sizes in quite small increments just by mixing and matching cylinders and crankshafts of different dimensions, without worrying much about bore to stroke ratios.
And some car engines are still oversquare, because it turns out to be the only way to get a large capacity into a small overall package size.
