“Best AI writing tool” is a broken question. A lawyer polishing client emails, a marketing team shipping forty ad variants and a startup keeping its wiki alive do not have the same problem. Here is the field sorted by job, not by hype.
The field at a glance
| Grammarly | Jasper | Notion AI | Claude | |
|---|---|---|---|---|
| Job | Polish what you type | Marketing copy at scale | AI inside your wiki | Deep writing and analysis |
| Entry price | Free; Pro from about $12/month annual | From about $39/month per seat | About $10/member/month on top of Notion | Free; Pro about $20/month |
| Lives | Everywhere you type | Its own workspace | Inside Notion | Chat and documents |
Polishing: Grammarly
Grammarly is not the smartest writer in the room, but it is the one that is always in the room: browser, Office, email, nearly invisible. The free tier already catches the embarrassing errors. For non-native English professionals shipping client-facing text, the paid tier usually earns its fee. Its ceiling is real: full rewriting is weaker than a top assistant, and corporate style guides need the pricier business tier.
Producing at volume: Jasper
Jasper sells the workflow around the model, not the model. Brand voice controls, campaign templates, team approvals: features built for marketing teams, not tinkerers. That is also the honest critique. The underlying models are the same ones you can reach directly for less, so a solo writer paying about $39 per month is mostly paying for process they do not have. Buy it for the marketing team, skip it for yourself.
Writing where your notes live: Notion AI
If your company already runs on Notion, the AI add-on answers questions across your own workspace, autofills databases and summarizes meeting notes without any switching cost. If you are not a Notion user, it is a non-starter, and as a pure writer it is good rather than best-in-class. Decide on Notion first. The AI is a second decision.
Deep writing: a general assistant
For long documents, careful arguments and manuscripts, a general assistant like Claude out-writes the specialized tools; that is what it is for. Contracts, reports, chapters: the pattern is to draft and think in the assistant, then let Grammarly catch the typos on the way out. The two layers do not compete.
Our recommendation
- Non-native professional, mostly email and client documents: Grammarly Pro, nothing else.
- Marketing team of three or more producing campaigns weekly: Jasper, evaluated against a shared general assistant first.
- Notion-first company: the Notion AI add-on is a no-brainer; do not buy it anywhere else.
- Writers, analysts, anyone whose work IS the text: a general assistant such as Claude, with Grammarly free as the final safety net.