Why we picked Gemini Flash over GPT-4 and Claude for the rewrite engine

Sharing our model selection process for Humanizer in case anyone is making a similar choice.

We tested all the major models on the same humanization task, paste a stiff draft, return something natural that keeps the original meaning. Three things mattered.

1. Speed. Gemini Flash is roughly twice as fast as GPT-4 on long inputs, which kills or saves the live edit feel.

2. Context window. One million tokens means a full essay or article fits in one pass without chunking. Chunking introduces seam artifacts at the boundaries.

3. Pricing. Gemini lets us offer a real free tier (a thousand words per month) without burning margin. The same volume on GPT-4 would have priced us out within a week.

Claude wrote beautifully but tended to over edit, rewriting sentences we wanted preserved. ChatGPT matched on quality but the latency made it feel laggy in the live editor.