Best method for same day purchase

What brokerageir accounts do you guys like for timing your buys? Coinbase takes like 3-5 days to officially receive my money from the bank. Then when it's sitting in the USD account it's making no money.

If you wanted to put a chunk if cash in a BTC brokerage for instant buys, are there any accounts offering 3-4%?

Or an overall better way to do this?