What's the best way to remove boards with stripped screws?

I can't for the life of me figure out how to remove these without taking forever. I have tried drilling around the screws, using a sawzall (Ryobi one is underpowered as hell), and some prying. It's too time consuming.

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What's your suggestions on how to quickly remove boards with rusty stripped screws from the joists?

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I'm working entirely with Ryobi and I can't help but feel it's all underpowered.