There are numerous options you will need when even creating the most basic site and its good to know that there are great quality options out there.
The plugins listed in the following areas I have used personally and I highly recommend them based off: Quality, Support, Compliance, Following(community using it/updating/adjusting) and versatility.
Essential WordPress Plugins for a Strong Website
- Advanced Custom Fields
Every wished you had an additional WYSIWYG editor on your pages or posts? Truly have your own “Content Left, Right, etc”. This is the perfect tool for you. They have strong documentation, premium add-ons and a great following as well as support. - WordPress Pro Event Calendar
Simple Enough. Works in IE7 and up. Responsive. Amazing support. Calendar specific options. This is a must even a client wants the most basic of calendars. - Gravity Forms
Arguably the best forms on the market in my opinion. Great list of features such as: Importing/Exporting entries, Forms with conditional logic, Accepting Payments, Custom post forms for user generated content. The list goes on and on. Great support/following/etc. A must for forms. - RoyalSlider WordPress
This in my opinion is one of the best sliders you can buy hands down. Quick and dirty on it: Responsive, IE7 and up, Great options and transitions, Easily create unique mark up for sliders and the list just goes on. If you need a slider to use on your site this is the one to use!