What you actually buy above $20
At $100 and up you are not buying a smarter default model. ChatGPT Plus already runs GPT-6 Sol in Chat, and Claude Pro already includes Opus 5.5. You are buying three things: more usage per window, access to the most expensive model tier (GPT-6 Pro on ChatGPT, a larger Fable 5.1 share on Claude), and agent or speed features that only exist on the top tiers.
That makes the decision a usage question first. If you do not hit your $20 plan limits at least weekly, a $100 tier mostly buys peace of mind. If you hit them daily, the $100 tier usually pays for itself, and the $200 tier is the answer only when the $100 tier also runs out in a normal week.
Claude Max has one extra that changed on October 7, 2026: monthly API credits ($100 or $200). They are useful if you also build on the Claude API, but Anthropic says they cannot be spent in Claude Code or the Claude apps, so do not count them as extra chat capacity.