As I shop around for jeans, there are many requirements before I purchase such pants. There is one thing in particular I look for first. In my opinion the most important thing is the fly type. It must be a zipper for me.
I know there are downsides of the zipper fly. The potential dangers of the zipper fly exist. The thought of it breaking (YKK zippers are pretty reliable though) could cause quite an embarrassing scene with an open fly all night. But the most risky part of a zipper, for males at least, is causing pain to one's self. An experience that I will never ever forget! I worst part of it was unzippering it. Good thing I'm not a fast zipper!
The positives of the zipper fly definitely out way the upside of the button fly though. The button fly eliminates the the hazardous unwanted catching of the zipper. But this seems to be the only true positive. While zippers can break, buttons can fall off. Button flies don't even compare to the convenience of zippers; buttoning three to four button is much tougher than pulling a zipper. Plain and simple, zippers are the best for males and doing the number one. While you do risk of getting it caught, it's worth the convenience really; in my entire lifetime so far I've only had this problem once. And all I have to do is be a bit more careful, which is still much less effort than the button fly. And is not to mention the odd feeling with wearing pants with a button fly, you can sometimes feel it's a button fly.
So, if you ever plan on gifting me a pair of pants, they better be zipper fly-ed. (Seriously though, I will be really thankful to receive any pants)