When it comes to plugins, we should consider 2 factors:
As far as WordPress plugins are concerned, quantity matters. Every plugin you install is another chance you'll see issues on your site.
Not only can they cause issues by themselves, but they can contribute to site-wide issues like load time and up-time.
WordPress plugin quality matters too. You could have a lot of plugins installed and see very few problems on your site.
Plugins that undergo regular updates and are supported by quality WordPress developers are always better.