As per my point of view plugins are those whose give you more functionality to your website.

So, choose those plugins which enhance your website and it’s looking for bloggers, online stores and many other websites.

I have used these three WordPress plugins which help me to reduce my work.

Blog Designer PRO for WordPress: Blog Designer is an effective and user-friendly way to beautify your blog pages on your websites. It’s a very popular plugin for website’s WordPress blog to attract more clients as well as more blog visitors. Blog Designer makes your blog section more intuitive with no coding skill.
Avartan Slider – Responsive WordPress Slider Plugin: Avartan Slider is a responsive WordPress plugin to create innovative and stunning layered content image slider and video slider. This plugin is an effective and user-friendly way to beautify your home page, header/banner section, and showcase on your websites
User Activity Log PRO for WordPress: User Activity Log Pro WordPress plugin is a powerful and strong monitor system to track your users and team activities. It helps you about WordPress core updates, Posts & Pages updates, User activities, etc. which are done in admin side for any WordPress powered website.
I hope it helps you too.