Start with where your users already are
The honest answer to "iOS or Android first" is almost never about which platform is technically better — it's about where your specific target users are. iOS tends to lead in North America, Western Europe, Australia and Japan, and among users who spend more on apps and subscriptions. Android leads by a wide margin globally, especially in South Asia, Southeast Asia, Africa and Latin America, and among users who prefer free or ad-supported apps.
Monetization model changes the answer
If your app is paid, subscription-based, or sells physical/digital goods, iOS users historically spend more per user, which can make iOS the better first platform even in markets where Android has more total users. If your model depends on scale, ad revenue, or free-to-use adoption, Android's larger install base usually wins.
Design and review process differ too
iOS apps go through a more opinionated design language (Human Interface Guidelines) and a manual App Store review that can take a few days and occasionally requests changes. Android's Play Store review is faster and more automated, but device fragmentation (screen sizes, OS versions, manufacturer skins) means more testing across devices.
Our recommendation
Unless you have strong evidence your users are overwhelmingly on one platform, we usually suggest starting with a single Flutter codebase that ships to both iOS and Android from day one — it removes the "which first" decision entirely for most early-stage products, and you can still go native later if a platform-specific feature demands it.