Pro:
- Relatively light at 1.4M
- Made in PHP, easy to deploy
- Tons of features for page organization
- Incredibly easy to make themes
- Ships with extensive documentation
Con:
- Setup via PHP config file
- Handling attached files is clumsy at best
Pro:
- Very light at <200K!
- Made in Perl, easy to deploy
- Ships with literally hundreds of plugins
- Built-in blogging support
- Trivially themed by editing one stylesheet
Con:
- Setup requires adequate technical knowledge
- File attachments are best used sparingly
Pro:
- It's just a self-contained web page that can save itself with all changes!
- Lots of cool, unusual features
- Less bureaucracy: there's no installations, logins or page history
Con:
- The Classic 2.x line has long-standing bugs and is limited.
- The new 5.x line is big, slow and complicated to use.
Pro:
- Made in PHP, easy to deploy
- Excellent media manager built in
- Comprehensive control panel
- Built-in source code highlighting
Con:
- Relatively heavy at 17M
- Difficult to make templates for
Pro:
- Easy to run locally via Python
- Rich markup built-in
- Decent handling of file attachments
Con:
- Not easily deployed on shared hosts
- Few themes available, hard to even install
Honorable mention for being another tiny wiki hosted on Ctrl-C.