An effective design process leads to a solution that addresses the actual human problem.
I believe that a "design process" depends entirely on the company's internal infrastructure, product, development life cycle, and business goal.
Design thinking process
Above all, I like Design Thinking process the most of all other UX design processes. Because, design thinking is one of the most well-known design processes of User Centered Design (UCD). The steps involved in Design Thinking are almost identical to the overall steps of the User Centered Design (UCD) process.
Design Thinking Process
Design sprint
Other than Design Thinking, I also feel comfortable using the Design Sprint process. The main purpose of running a Design Sprint is to validate idea/feature within a week before it is implemented. Design Sprint helps to validate product decision in the early stage before it fails. I like Design Sprint so much that I have written an article on it in Medium.
Design Sprint
Double Dimond framework
I think every UX designer should know about the Double Dimond framework. Because Double Diamond model is a framework that can be used in a variety of industries and just about anywhere. It’s more than a simple tool for any designers, because it can be applied to any problem that calls for a solution. Double Diamond is a more traditional UX process, which breaks down UX design into two main phases (or “diamonds”): research and design. 
Double Dimond Framework