Want to start a fight among mobile/digital photograhers? Just ask them which is the best photo app. There are zillions. But in our opinion, nothing beats Adobe Lightroom for manipulating high-res images in-app, post-processing. Lightroom might not be the cheapest, but it’s arguably the best. See the iOS version at https://apps.apple.com/us/app/adobe-lightroom-photo-editor/id878783582. Android is available now too. Both are free — sort of.
7) For Capturing Still Photos on Mobile, Nothing Beats Lightroom

Also check out FirstLight from the folks who brought us the very best mobile video shooting app, FiLMiC Pro.
Lightroom is, indeed, a great mobile photo editing app, but its feature set is crippled without a paid Adobe Photography plan ($10/mo gets you Lightroom, Lightroom Classic, Photoshop, Photoshop Express and – most people don’t realize it – Adobe Spark — best software subscription deal on the planet): https://www.adobe.com/creativecloud/photography.html.
BTW, those wanting to learn a bit more about shooting images and/or video, check out the free curriculum from the Mobile Ministry Forum at http://www.mobmin.org/train (under the DIY Media section). Also check Mission Media Coach at http://www.mobmin.org/mmc.
Wow – it had been some time since we’ve tried FirstLight. They’ve come sooooooooo far with it. I think, in my book, Lightroom still beats it for post-processing (integrated) – but I have to admit… FirstLight’s capturing interface is soooooooooo intuitive and powerful! You’re right though – if a person isn’t already paying the $10/month photography plan, FirstLight takes the cake. Thanks Brian!