Which PM should pick which model in 60 seconds?
**Pick Claude 4 Opus if** you write PRDs read by engineering and design before sprint planning, you synthesize qualitative research, or you draft exec memos that land a decision in one read. Claude's long-context coherence and restrained tone are what PMs notice first.
**Pick ChatGPT (GPT-5) if** your week is dominated by quant — A/B readouts, retention cohorts, churn memos leaning on a CSV — or by generating hypotheses, opportunity-tree branches, and OKR drafts. GPT-5 plus Code Interpreter on a CSV is the fastest analyst on staff.
**Run both if** you manage a team across discovery and delivery. Combined cost is $40/month — less than one re-run sprint that picked the wrong bet.
Test either model on a real PM brief with the free ChatGPT Prompt Generator before you commit a seat.