A good resource is this: https://artificialanalysis.ai/?cost=intelligence-vs-cost-per...

Go to the "Cost" -> "Intelligence Index vs. Cost per Intelligence Index Task" That diagram maps their "Intelligence" score to "cost per task" and I think this gives a good basis on deciding with which model you want to go. Then you can either get an API token from that models provider directly or use openrouter and set openrouter to the model/providers of your choice.

You can also see on openrouter itself the details for each model like prices and what providers are offering it at what price.

Finally you can compare models details using openrouters compare feature like this:

https://openrouter.ai/compare/anthropic/claude-opus-5.5/open...