ProcessWire vs Drupal

You will always find one to respond politely in the forums. Sometimes even the creator Ryan Cramer himself.

ProcessWire is heavily based on custom fields. All objects (Pages) inside ProcessWire are based on extensible templates comprised of fields that can be easily defined. Many useful fields come prebuilt and they can be extended with modules.

Processwire is extremely easy to learn. Consider this:
echo $pages->get('title=Hello World')->title; // "Hello World"
echo $pages->get('title=Hello World')->parent->title; // "Home"
echo $pages->find('Template=Category')->count; // 126
echo $pages->find('Template=Category')->each('title'); // ['Audio', 'Video' …]

Selectors are so powerful but yet so easy.

Check out the cheatsheet.

The API is jQuery like;
// find some pages:
$pages->find('template=skyscraper, architect=john, sort=title')->limit(4);

// mutate
$pages->get('title=Hello You')->set('title', 'HelloWorld')->save();
$pages->get('title=Old')->trash(); // trash page

// check user…
$user->isLogedin();
echo $user->name; // guest
$session->login($name, $pass);
$session->logout();

// redirect
$session->redirect($url);

The way you fetch, access and manipulate objects (Pages) in ProcessWire is extremely powerful and easy. You can receive any page and its custom fields, filter, travers, add…

By default, ProcessWire comes with 0 assumption on how you handle the output. You have 100% freedom on how you want to develop the frontend. Want to plain output stuff, go ahead. Want to use any number of Templating Engine, do it. Just use as Headless-CMS, okay!

Either using the modules already available or writing your own module, using the jQuery-like API.

Source available on GitHub.

Drupal is stable, with powerful version control and access control methods and can handle large amounts of traffic.

Drupal is free to use and open source.

Drupal have one of biggest and more active communities across FOSS, maintaining a large and vibrant ecosystem of extensions and installation profiles.

Twig is a game changer!

Starting with Drupal 8, there's built-in multi-lingual support.

Drupal can be customized to do almost anything. It was built ground up with the intent of using a wide variety of small modules to get the exact result wanted instead of just the most common solutions.

Drupal 8 has REST services built in.

(vs Joomla, which lacks SEO capabilities), there is an essential issue for promotion.

Drupal was designed from the beginning to follow best practices in regards to SEO.

Drupal 8 follows responsive design philosophy out of the box, both front-end and back-end.