Need a guidance for the career development in Testing

I want to develop my career more in testing domain,I have 4 years of experience in testing domain and i want experts suggestion to take correct decision to learn more in Testing side. my question is i want to learn some new technologies in Testing which is available in market. so can any body guide me which technology i can learn based on my experience.

My Experience:

Manual Testing (UAT) : 3.3 years Automation (Selenium Webdriver and Protractor-cucumber js Framework) - 3 years (parllaly with manual)

so f i want to learn, which course will be more suitable for me?