Have a look at some of the most popular ones (so that there's a higher chance you might find them useful, too).
- W3 Total Cache: This is a must to improve your website's speed. It deals with stuff like browser caching, code compression, improved rendering in your behalf, and this will greatly improve your website overall speed (as well as web server performance).
- Yoast: I know, this is for SEO, too, but it can be used for much more than that. First of all, it improves stuff like RSS, it can help you modify your robots.txt and .htmaccess files more easily, and it will also help you write better articles (as in, more search engine optimized one), especially when dealing with descriptions.
- Akismet: If you have a comment section, then you also need this. This plugin will automatically check your comments to see if they are spam or not. This plugin is free for personal websites and paid for business websites.
- Captcha: Pair this with Akismet to avoid possible spam comments completely. It does exactly what you think: puts a captcha people need to answer before commenting.
- Contact Form 7: If you need feedback but feel like comments are not the right thing for you, then how about one of the good, ol' contact forms? You can customize them any way you like, and you can use Akismet and Captcha to avoid spam with this, too.
- BackWPup: Sometimes, things go wrong, and so we should do everything we can to minimize the consequences: this is why backups are fundamental. With this plugin, you'll be able to periodically save all your important stuff in a nice .zip file you can easily restore on a FTP server, Dropbox, Google Drive and much more. This is particularly useful for news websites, since you most likely won't be able to save every single article you write somewhere (either online or offline).
- Slider Revolution: You never know when you'll need a slider on your website. It can be a nice way to display images or thumbnails for your news, and you won't have to code anything!
- EWWW Image Optimizer: If your website has a lot of images, there's a chance they may slow it down a lot, so we absolutely have to reduce their weight. This plugin will optimize PNG and JPEG images with almost no quality loss. This is highly recommended since image size is a parameter analysis tools like Google PageSpeed Insights take into account to give any website a score.
- WPFront Scroll Top: If your website has long pages, then adding a nice scroll-back-to-top button will make navigation much easier for viewers, especially on mobile. You can customize the way the button looks (you can even use a custom image), when and how it appears, the scrolling animation and much more.
- Cookie Notice: If you're going to monetize your website with ads, because of the recent change to cookie law regulation, you'll need to notify your users about that. This plugin will let implement it and customize it (displayed text, appearance, colors, etc.).