DeepSeek also has APIfied subs, and they have competition in-between so customers can have a great price.

I had a check on artificialanalysis.ai and it shows a 16% reduction in token and 200% increase in time for Opus 5.5 Max compared to DeepSeek V4.1 Flash Max. I don't think the data is very accurate for my real life workload, but for any workload it represents I would think Opus having little advantage.