I've swapped to the 20x Claude plan for a month or two to knock out two ideas I need to get it MVP - expecting Claude to go token priced soon.
At my company we did the comparison and Copilot still wins: for 20$ you get a seat and 20$ of usage, whereas with Claude enterprise you get a seat and then usage is completely added. Moreover usage in Copilot is exactly the price of the providers AND it allows us to use various models from multiple providers.
The case that might be less expensive is if you negociate a volume discount with AWS for Bedrock usage, but that is also possible with GitHub and Microsoft.
Edit: wording on the cost saving effort
How is that possible? AFAIK copilot charges the same price per token that claude does. They don't offer fixed price subscriptions to enterprise customers (again AFAIK but even if they did presumably they would match the price).
The only exception I'm aware of is volume discounts and you can get those from both copilot and bedrock (and presumably also vertex).