Set up business email name and link to domain

I have a registered business domain (website not yet built). I want to establish a business email address to send to clients. I'm unsure whether to establish the business email address on Google Business then link to my domain or to establish on domain cpanel then to push to a business address in Google (not yet established)? I want to be able to access my business emails from my phone and Mac without signing into my cpanel to access emails. My host is Fast Comet and they told me last night to establish email in cPanel then push to another email address but I'm not sure if better to establish it via Google Business. Also need to consider I am building an email list and want this to be easily transferable to Kajabi, Ontraport or best email marketing platform. I need help deciding best way to do this then setting it up. Thank you :)