Buying $300k in BTC next few months. Which broker?

I plan to buy around 4-5 BTC over the next few months. Maybe do it in 3 chunks. Its a long-term HODL. Main goal is low fees and future access to products like borrowing against my BTC or even using it as collateral for a mortgage 2-3 years down the . Maybe want a little bit of margin.

Leaning towards Kraken but want any and all recommendations! Also, I have a Ledger USB already