These days, app makers must contend not only with well funded giants in the mobile space, but with the endless amount of new competition entering the scene as app store growth accelerates. Once a better version of your app gains popularity, yours is likely getting the axe—especially when the daunting “Storage Almost Full” message appears. To avoid the chopping block but not waste precious resources, you have to prioritize. So, which matters more: design or function?

Computer, tablet, and smartphone users tend to be both decisive and loyal. For years, we’ve seen the same major brands go head-to-head, but this point buyers have generally chosen their camp. Try to sell a longtime iPhone user on an Android (or vice versa) and you’ll find yourself wrapped up in an endless debate over features, UI, customization, battery life, security, the color of the message bubbles…

When it comes to apps, the market is endless and users are far less forgiving, especially when installing is free and uninstalling is simple. Once dominated by professional designers, the app industry is now accessible to anyone with a computer and some time on their hands through DIY app builders like Bizness Apps. So with such a high degree of market saturation, how can you entice users to download and keep your app installed for the long-run, especially when gaining loyalty is much harder?

Function Breeds Loyalty

When a new user launches an app, they form an opinion immediately. Is it easy to use? Is it visually appealing? Does it perform all the functions I need it to? The average user doesn’t want to spend more than 10 minutes figuring out how to use an app and there’s no barrier to uninstalling which makes user experience of chief importance in retention. Recent findings by TechCrunch suggest average users spend 85% of their smartphone time on native applications, and 84% is devoted to just five apps total. Each user’s “fave five” will vary considerably, of course, but the apps with the highest usage fall under the categories of social media, gaming, and instant messaging.

Mobile apps can edge beyond the competition by doing one thing—and doing it well. Consider e-commerce; since mobile websites often facilitate easy purchasing, mobile apps need even simpler checkout processes to be attractive to the average user. That means reducing the number of clicks to the purchase page, storing account info, and generally providing a much more personalized experience. If a user has installed a retail app, they’re likely looking for deals and an improved purchasing process. The app needs to check those boxes to stay on the home screen.

Design Closes the Deal

Fellow designers and mobile experts are sold on apps for entirely different reasons. Many industry buffs are most impressed by an app’s ability to draw on the device’s existing features, improving or applying them in new ways. For example, camera apps that optimize flash and size often top the design charts. Gaming apps are still popular in this demographic too, but generally for their innovative design and graphics. And though the general public tends to discount design in favor of the function-packed these days, the nuance of design is very much alive.

Remember the message bubble thing above? It may seem silly that the background color of a text message would merit a reaction (and an emotional one, at that), but I can’t tell you how many iPhone users have expressed actual hatred for the green bubble that appears when they text non-iOS users. The message bubble defaults to blue when you’re texting another iOS user—a genius little trick on Apple’s part that glorifies its own. When applied to mobile apps, this psychology suggests that design holds the power of long-term influence. Users may be drawn in and initially held by an app’s function, but design can lock them in as they gradually develop a UI preference that they can’t imagine swapping out for something new.

What This Means for You

Average users want instant gratification and answers to their specific needs, but craftsmanship and visual innovation have more subtle capabilities in user retention. If you’re operating on a slim budget or a time crunch, your top priority should be perfecting function. Give users a reason to download and a reason to come back, and you’ll make a bigger dent than you would with an app facelift. But if you can devote more energy to your mobile app, don’t overlook the potential small design changes have to radically improve user experience. With three million apps and counting, there’s something out there for everyone, but you can’t beat a good first impression.