Which do I sell? Tax implication for losses (cost basis)

Hello! My portfolio has regularly purchased stock (ESPP and RSU) for the last 10 years with steady rising price. Now that stocks have fallen, I am unsure which make sense to sell (funds needed for side investment).

I have A. some that will sell at a loss (cost basis significantly above current price), B. some that are equal to todays price, and C. others that are well below todays price (higher capital gains).

I’m wondering if I sell at a loss, would that be helpful for taxes? Should I aim to sell the ones that are near todays price?

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