Lowest cost BTC exchange for direct to cold wallet purchases

When comparing BTC exchanges it's generally easy to determine transaction rates but it can sometimes be less straightforward to find withdrawal rates (meaning BTC direct to cold wallet, not fiat to your bank account.) Sometimes withdrawal rates will negate low-cost transaction fees, Kraken being one example.

Who is the best for the scenario of a BTC purchase that will be immediately sent to a cold wallet? I think Strike had no withdrawal fees at one time and I can't find any such info in their fees listing, but not sure if their recent fee structure changes affected this. Who do you use for off-exchange purchases into your cold wallet?