I will suggest WordPress as the best web development platform available today.
WordPress is so popular, There are tons of themes, plugins, tutorials support and they even have wordpress.org which is free.
But as suggested in this thread, the popularity of WordPress has become it's greatest threat, as hackers and spammers target wordpress websites more than ever.
There are vulnerability issues in wordpress, but they are constantly updating the platform and closing all backdoors opened by vulnerable plugins.
If use WordPress sensibly, it is the best. If you go on and install a lot of plugins with no history or good reviews you might as well be in danger.
There are a few precautions that you can take to keep your wordpress website safe, and make the most of this amazing web development platform.
You can read bout the safety measures that have to be followed in wordpress here https://www.globalme...s-website-safe/
Basically, don't use default user names and passwords.
The URL for back end access in wordpress websites are all same, yourwebsite/wp-admin
So hackers and spammers can easily try common user names and passwords surprisingly most people still use.
Like admin, admin123 etc... those are silly mistakes to make from your end.
Using "Recaptcha" for form and comment submissions are also a very good practice.
There are other good web development platforms like weebly, drupal, joomla but wordpress towers all of them.