ZenNMotion

Eyelets prevent the spokes from being pulled through the rim, so you can make a tighter (stronger) wheel with them. Eyelets also prevent water and road grit from getting inside the rim, a consideration if you ride in the rain or off pavement. But if you're just riding a fixie in the street, and don't plan on seeing much wet weather you can choose- you get what you pay for. Alloy spokes don't really make that much difference in weight/performance over standard brass, especially for a fixie that doesnt see real steep hills or racing. But they come in colors, so they can look cool. But easier to strip than brass, and more likely to weld/oxidize themselves to the spokes over time than brass, so they're not as practical for long-term longevity.