CRM Implementation

Hi

I am starting a sales agency, and therefore I'm looking for an CRM, that I can use for my company internally and also for my customers. So I want to provide my customers an CRM system to improve their sales processes, for which they pay me a monthly fee (because I have to pay the system in advance). A white label solution would be great, so that I can sell the system with my own domain, logo, etc. And of course it should have functions like (E-Mail) Automations, Dashboards, etc. Which one is best for that case?

Thanks for your help.