Dealing with the app stores. Hands down. The DUNS number, the certificates, the keys, identities, and profiles, the app review, the maintenance and updates on e

Dealing with the app stores. Hands down. The DUNS number, the certificates, the keys, identities, and profiles, the app review, the maintenance and updates on ever-changing APIs, SDKs, xCode, etc. Their needless updates will outpace your ability to keep up. Anything to do with the actual code of your app is fine. Once you have to interface with Google and Apple, it's an endless nightmare.