All that truly matters is where you hold (cold storage). Buy from whoever is cheapest and has fastest withdrawals.
Discussion
Cash app is the fastest hands down. From my bank to cash app in seconds, from cash app to Bitcoin in seconds, from cash app to lightning in seconds, from lightning to liquid with bolts in seconds. Funds are 2FA in my liquid until I either move a portion to cold storage or back to lightning. I limit my liquid storage to 5mil sats, lightning 500k in Alby and the rest goes to cold.
Show me a way to get $ from my bank to liquid Bitcoin faster than 5 minutes and I will go there. I hate waiting for an ACH to settle before I can access MY MONEY on traditional rails.