You have a choice of your fly. Both are great options, it's just up to you to decide what works best. Buttons are more traditional. Zippers are a bit easier. Either way works well.
History of buttons & zippers
The very first jeans made by Levi's in 1873 featured a button fly. Though zippers were invented in the early 20th century and in wider use by the 1930's, Levi's didn't offer zipper flies in their jeans until 1947.
DDCo. only offered button flies for the first 8 years and introduced zippers flies in 2018. Over the years, we've heard both sides of it: from the "button fly 'til I die" crowd, to those who will only wear zippers, to those who have no preference.
So which do we recommend? We don't, really. It all depends on your personal preferences. Around here we tend to prefer button flies because we love to dork out on historical accuracy in garments, and also because they're more durable and easier to fix when they do need a repair. But we also love a good zzzzzip!
Here are the pros and cons of buttons and zippers flies: