Personally, I think that Coinbase will become more popular because it's number two exchange by popularity at the moment and what makes it more attractive compared to Binance is that it's the San Francisco-based company, has been in business since 2012.
I can say with great certainty that you can exclude Coinbase from this possibility, because they have too many restrictions and limits for users. Especially after
the announced closure of many accounts after April 9.
to achieve a dominant or approximately strong position requires a global business, Coinbase certainly does not have that, they will remain only as a solid online wallet.
For instance, as of now, the current BTC price is $28,110 USD[5] where in Bisq the value is sitting at ~ $28,701 USD[6] (2% increase). Due to the nature of the platform you'll likely encounter sellers that impose a higher %, but from what I've seen that is more often than not related to the quantity you are purchasing (the bigger the smaller the % of the premium), which is understandable.
the current price is what someone is ready to pay at that moment. you can't just compare, because there are differences between open orders and executed ones. if it were so black and white, I believe that arbitrage trading would be an easy job.