Comparison of meta tag modules

There are a lot of Drupal modules that help site builders to configure site-wide meta tags, to create contextual meta tags, to create custom meta tags, and to control these tags through various kinds of user interfaces.

Nodewords

Add meta tags to Drupal pages, both manually and automatically, based on various settings. D7 users should use Metatag.
Drupal core:
Development status: No further development

Metatag

Meta tags implementation based on Token.
Meta tags currently provides tags only on nodes (front page, users, taxonomy term, node). However, other modules have been created to extend its functionality.
Drupal core: 8.x, 7.x
Development status: Under active development
Supported tags: Canonical URL, Copyright, Description, Generator, Keywords, Open Graph Protocol, Publisher URL, Robots, Shortlink URL, Title

Meta tags quick

Meta tags implementation based on Fields API
Every meta tag (keywords, description, copyright) is treated as a separate field. Meta tag fields are then attached to registered entities (content types, taxonomy vocabularies), and appear in the entity edit form. Pages that do not represent any entity (default front page, views etc.), are served using artificial entity 'path-based meta tags'.
Meta tags quick does not support Token, so fields here will not accept tokens. This module also has a long standing uninstall issue, see 1341252.
Drupal core: 8.x, 7.x
Stable version: 7.x-2.9
Development status: Under active development
Supported tags: abstract, copyright, description, keywords, revisit_after, robots
Mechanism to extend supported tags: Fields API
Supported pages: All non-administrative pages
Upgrade path: Import of nodewords data (only tags listed above)
Global defaults: No
Default values: Limited (using Fields API interface)
Token support: Yes
SimpleTest: No

Custom Meta

Define and manage custom meta tags. Useful for adding the same meta tags to every page, or for creating custom meta tags that contain field data (via tokens).
Drupal core: 7.x
Development status: Under active development
Supported tags: Any
Token support: Yes

BeansTag

Simple management tool for page title, meta tag and meta description. All meta data management is done on a single page. Supports any pages: nodes, view pages, panels.
Drupal core: 7.x
Development status: Maintenance fixes only
Supported tags: title, keywords, description
Token support: Yes

Simple Meta

Drupal core: 7.x
Development status: Under active development
Supported tags: title, keywords, description
Token support: No

Page Title

Granular control over page title. Specify patterns for how the title should be structured and, on content creation pages, specify the page title separately to the content's title. Use tokens to for title per content type. Append page number as a suffix pattern for views pages. Comes with a page title API.
Drupal core: 7.x
Development status: Obsolete
Supported tags: title
Token support: Yes

Context Metatags

Based on the Context module, provides flexible meta tag creation for title, description, keywords, robots, and provides filters (trim metatag character length, lowercase keywords).
Drupal core:
Development status: Maintenance fixes only
Supported tags: title, description, keywords, robots
Token support: Yes

Context Metadata

Set title, description, keywords, and canonical URL metadata tags using a context. Set meta data per path for custom callback pages, dynamic view pages, Panels. Compatible with Nodewords and Page Title.
Drupal core: 7.x, 8.x
Supported tags: All tags supported by Metatag modules
Token support: Yes

Integrated Meta Tags

There is an issue asking about duplication over at #228768. It does not appear to be a duplicate in that it uses a different methodology to generate the tags.
Development status: unmaintained