Nobody preinstalled an agenda on your iPhone. That is the advantage: four free downloads and one honest afternoon gives you a real answer. ChatGPT, Claude, Gemini, Perplexity: go. - Test the iOS-specific plumbing: Shortcuts integration, the share sheet, voice input quality on a walk. The app that slots into your habits wins, even if its benchmarks are a hair lower. - Rough guide: Claude's app shines at writing tasks. The ChatGPT app is the best all-rounder with the deepest feature set. - Gemini is worth it if you are a Google Workspace person despite the Apple logo on your phone. - Perplexity is the research specialist. An AI tool comparison quiz app on iOS and Android can narrow the field, but the share-sheet test predicts daily use. My rule: keep two. One primary, one specialist. StackAudit recommends the optimal 3 to 5 tool AI stack for your profession with pricing and setup guides for $4.99 one-time unlock.