Thought of Prism Harmony's when I saw the post https://news.ycombinator.com/item?id=44549209 and wanted to share my own.

It does have unlimited usage for main models, up to 3 hours rate limits that are pretty clear on the account page.

(15 requests every 3h for premium models like o3 or Claude 4 Sonnet, 35 for models like o4-mini or gpt-4.1, etc.)