We administer a lot of WP sites, a few of our own and a lot more for clients.
Every site is different, and a lot of the lists that you find all over the internet of 'must-have' plugins include a load of stuff that most sites really don't need.
I do have a list of things that we use on the vast majority of sites, and they cover the same basic functionality as Lauren's list above, even if each individual plugin is different.
- LiteSpeed Cache - We run LiteSpeed servers, it makes no sense to use anything else, and it's image optimisation functions are better in my opinion than most of the dedicated image opt plugins, including Smush.
- VividWP - Backup, it offers a lot of the features that many of the other backup plugins put into their 'pro' plans for free. It also used to be less intrusive with upsell notices, but they are starting to add more of them now.
- Easy WP SMTP - Self explanatory.
- The SEO Framework - Does the same things as RankMath, SEOPress, or Yoast, but is light, fast, and has an interface that I personally like to use.
We also install a couple of our own plugins, one is a fork of MainWP Child, that lets us administer updates, etc. remotely on all sites from our MainWP dashboard, and the second connects to our Matomo analytics server.