The verdict
For a freelancer or a small business that writes many short pieces, I'd pick Rytr. It has a free plan, no card is needed, and the templates save you from writing a good prompt each time. For a sales or revenue team that wants research, enrichment and outreach drafting to run as repeatable workflows, I'd pick Copy.ai.
If you only need an occasional draft, you probably need neither, because ChatGPT or Claude does the job directly. Copy.ai has no free plan and is aimed at teams, so it only pays off once you can write down the steps you want to automate. Rytr will not plan a campaign or route drafts for approval, so you will outgrow it if several people write under one brand.