I think you need to think about the things to look for in a good designer first.

Different marketplaces are for different people. You need to know at which level you are, what are your goals.

Hunting the right designer/company for your UI/UX design project needs, itself is a big task as there are too many to select from. You need the check their proven track records for delivering really high quality services to a wide range of industries and organizations.

WebClues Infotech is leading user experience design company that serves global clients and can be your perfect partner in setting up a distinct KPI for you as per as UI designing, user research and UX process goes.

Website link: http://www.webcluesinfotech.com/