There are lots of good Addons to consider. Here is my list:
Circonians Addon Selector: If you use an addon that slows down things, (like harvester, or an auction addon), use this addon. You can create sets of addons to use, and quickly switch between those sets of addons. So if you want to go harvesting, have one set of addons that includes harvester. When you just want to do questing and not harvesting, choose the set of addons that excludes harvester, etc.
Combat metrics: provide insight to your damage output.
Dark UI: Ohh shiny. Purely cosmetic, but i like how it makes the UI look.
Dolgubon's Lazy writ crafter: Easy way to master writs
Dressing room reborn: can save your action bars and gear sets as unique sets.
Map pins: adds useful pins to your ingame map skyshards, lore books, dungeon bosses, etc, etc, etc)
Urich's Skill Point Finder: shows graphically all the skill points you have (and have not) earned.
Votan's Minimap: Gives more functionality to the minimap.
Votan's Keybinder: assists in creating a user account-wide shared keybindings. (helps keep keybinding the same across characters).
Votan's Search Box: enables built-in search box of your inventory
Untaunted: shows a frame of your enemies you have taunted and the time remaining for each taunt.
Master Merchant: auction house addon
Harvestmap: self explanatory
Inventory insight: nice addon for altaholics. Tracks everything in your characters bags, bank, craftbag, storage chests, etc.
Action Duration Reminder: track sloted actions that hvae over time effects; reminds you to re-invoke your actions; helps you in your rotations.
Champion Point Respec: allows you to save your current CP allocation to easily switch between different allocations.
Hope this gives you some more ideas for addons. I also recently started using Minion. Love it so much.