No problem using both. Safari excels at its integration with everything Apple does, primarily iCloud Keychain, its "strong password generator", and automatically filling in annoying 2FA codes. Brave and FF excel at customization.
You can even export Safari's saved passwords and subsequently import them into Brave, making it easy to alternate between the two. I'm sure there is a way to do that with Firefox also.
Be advised passwords will not be encrypted in transit, but that much ought to be obvious.
Plenty of other browser choices. Dissenter and DuckDuckGo are among those I have some experience with. Arc, Edge, and Opera I have not.