I run many Obsidian plugins and they're constantly changing. These are the ones that have stuck around.

• Copy as HTML
  • I treat this as “copy with formatting” so I can copy e.g. bulleted lists from my notes and paste them into an email to send to others; without it, the copied text is unparsed markdown
• Editor Syntax Highlight
  • Syntax highlighting for fenced code blocks, just like GitHub
• Excalidraw
  • Unbelievably well-integrated Excalidraw support; embed drawings in notes but also let specific elements in drawings link to notes or dynamically inherit content from notes, and a lot more
• Global Search and Replace
  • Does what it says on the tin; I expect this will become a first-party feature soon
• Linter
  • Automatically apply Markdown linting on save
  • Cleans up inconsistencies like # line breaks between paragraphs, heading capitalization, re-index ordered lists, etc.
• Numerals
  • Adds a code block type for math, including calculating and rendering answers for each line
  • Basically Jupyter Notebooks for math; easy to show work and avoid mistakes since the answers are calculated on render
• QuickShare
  • Publish a note to an auto-expiring shareable URL
• Smart Links
  • Allows specifying patterns to automatically link
  • I use it so I can write e.g. OPSFLOW-123 to link to a Jira ticket
• I use the Daily notes core plugin, which adds a button/command to create a note for today with a predesignated place and title (e.g. Daily/YYYY-MM-DD.md). These community plugins extend that:
  • Daily Note Outline
    • A single pane that shows an outline of all daily notes in reverse chronological order
    • I have this persistently in my right sidebar
  • Daily Notes Opener
    • Auto open today’s note when opening Obsidian
  • Obsidian TODO
    • Collects TODOs from all notes (daily or not) and shows them in one pane
    • This is also persistently in my right sidebar
    • These are markdown todos, which Obsidian natively supports (e.g. - [ ] Go shopping); for a more powerful experience look at Tasks
  • Natural Language Dates
    • Type e.g. @yesterday or @tomorrow to link to the daily note for those days
  • Review
    • Mark the current spot (any note, any header) as needing review at whatever date you want (e.g. tomorrow); it will be added to that day's daily note
    • For a different workflow see Reminder