Google AdMob is a great choice. It offers a variety of ad formats including banners, interstitials, and rewarded videos. AdMob integrates easily into your app and provides strong targeting options. The platform also gives you access to a large advertiser pool and detailed analytics to track performance. With its mediation feature, you can maximize revenue by working with multiple ad networks. AdMob is a solid option for both beginners and experienced app developers looking to monetize their apps effectively.