Hi Romain,
I can't imagine creating a list of WordPress plugins that should be installed on every website. Generally speaking, each site's needs are completely different, and require different plugins and/or functionality.
That said, you might consider the Akismet plugin as one standard for most sites, since it effectively blocks comment spam, which can be become a real problem as a site grows in popularity.
And, you might consider the powerful, all-in-one Jetpack plugin, which includes dozens of features. But you'll likely only activate certain modules that add specific functionality for each individual site.
There are dozens of plugins that I recommend on a regular basis, but on a case-by-case basis, as the needs of a particular site warrant.
Hope this helps!
I use Akismet, XML Sitemap, Yoast SEO, Link Embed, and WP Smush.