glucose is a simple monosaccharide...and for anyone that remembers what fermentation is from bio class, the glycolytic breakdown of glucose to pyruvate is the necessary step for ethanol production. so...since sucrose is the combination of glucose and fructose, it requires a hydrolysis step, hence slower fermentation. so it is oft better to go with a monosaccharide. That said...yeast strains selectively prefer fructose over glucose or vice versa...it depends on your yeast. I am sure you are probably not going with some oddball yeast like Sauterne or those derived from S. pombe and S. exiguus. As those are the fructose prefers, stick with glucose...aka...dextrose...aka "corn sugar".